Pay vs Performance Disclosure - USD ($) | 12 Months Ended |
Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020 |
Pay vs Performance Disclosure [Table] | | | |
Pay vs Performance [Table Text Block] | Pay vs. Performance Table Summary Compensation Table Total for PEO (1) ($) Compensation Actually Paid to PEO (1)(3) ($) Average Summary Compensa- tion Table Total for non-PEO NEOs (2) ($) Average Compensa- tion Actually Paid to non-PEO NEOs (2)(3) ($) Value of Initial Fixed $100 Investment Based On: Net Income (7) ($) (,000s) Company-Selected Measure (8) (per share) Year Total Shareholder Return (3)(4) ($) Peer Group Total Shareholder Return (5) ($) Ms. Grow Mr. Anderson Ms. Grow Mr. Anderson (a) (b) (c) (d) (e (f) (g) (h) (i) 2022 4,441,045 4,725,667 1,326,582 1,435,286 110.06 117.09 259,560 $ 14.65 2021 5,645,525 5,564,659 1,977,637 2,297,255 112.38 115.76 245,872 $ 14.15 2020 5,903,347 6,318,341 3,114,307 20,653 2,351,741 1,473,753 92.53 98.84 237,968 $ 13.79 (1) Ms. Grow was appointed CEO in June 2020. Mr. Anderson retired as CEO in June 2020. (2) Non-PEO NEOs included in the average calculation are listed below. 2022 2021 2020 Steve Keen x x x Brian Buckham x x x Adam Richins x x x Jeff Malmen x x x Ken Petersen x (3) The dollar amounts do not reflect the actual amount of compensation earned or paid during the applicable year. The following adjustments were made to total compensation from the Summary Compensation Table ("SCT") for each year to arrive at compensation actually paid, as computed in accordance with Item 402(v) of Regulation S-K (in dollars). 2022 2021 2020 PEO Average non-PEO NEOs PEO Average non-PEO NEOs PEO PEO Average non-PEO NEOs Less SCT total grant date fair value of equity awards (2,092,631) (475,607) (1,714,845) (515,070) (1,371,935) (2,268,182) (466,880) Less pension value — — (1,760,278) (567,460) (2,711,412) (2,613,893) (1,069,692) Fair value of awards grant during fiscal year that remain unvested at fiscal year end (7) 2,494,680 446,824 2,675,143 803,500 1,293,581 208,203 440,209 Increase by fair value of awards granted during applicable fiscal year that vested during fiscal year, determined at vesting date — 9,960 — — — 86,365 — +/- By Change In Fair Value Of Outstanding Unvested Prior FY Awards That Remain Unvested At FY End Compared To Fair Value As Of Prior FY End (7) (79,170) (17,802) 760,964 301,104 (32,091) 25,610 (17,817) +/- For Awards Granted during Prior FY, determined based on change in ASC 718 Fair Value from Prior FY End to Vesting Date (7) (85,861) (50,052) (73,702) (41,379) 12,945 (72,566) 7,678 Deduction of fair value of prior fiscal year awards as of prior fiscal year end that were forfeited during fiscal year — (73,652) — — — (1,687,333) — Increase by amount of dividends paid on unvested awards during fiscal year prior to vesting date 47,604 11,399 31,852 11,567 19,872 24,108 9,238 Increase by incremental fair value of options/SARS modified during fiscal year — — — — — — — Increase by service cost and prior service cost (if applicable) for pension plans during fiscal year — 257,634 — 327,356 — — 219,276 284,622 108,704 (80,866) 319,618 (2,789,040) (6,297,688) (877,988) (4) TSR is calculated by dividing the sum of the cumulative amount of dividends for the measurement period (assuming dividend reinvestment) and the difference between our stock price at the end and the beginning of the measurement period by our stock price at the beginning of the measurement period. (5) Represents the weighted peer group TSR, weighted according to the respective companies' stock market capitalization at the beginning of each period for which a return is indicated. The peer group used is the EEI Utilities Index. (6) To calculate the fair value of our performance-based restricted stock unit awards, the probability of achievement in CEPS was re-evaluated annually. The valuation assumptions used to calculate fair values for the TSR component of the awards did not materially differ from those disclosed at the time of grant, except for consideration of historical performance-to-date as of the valuation date. (7) The dollar amounts reported represent the amount of net income reflected in the company's audited financial statement for the applicable year. (8) The company selected measure is CEPS. CEPS levels represent a key measure of performance for the benefit of shareholders aligning executive officers' management efforts to enhance revenue and contain costs with shareholders' performance objectives. | | |
Company Selected Measure Name | CEPS | | |
Named Executive Officers, Footnote [Text Block] | (1) Ms. Grow was appointed CEO in June 2020. Mr. Anderson retired as CEO in June 2020. (2) Non-PEO NEOs included in the average calculation are listed below. 2022 2021 2020 Steve Keen x x x Brian Buckham x x x Adam Richins x x x Jeff Malmen x x x Ken Petersen x | | |
Peer Group Issuers, Footnote [Text Block] | Represents the weighted peer group TSR, weighted according to the respective companies' stock market capitalization at the beginning of each period for which a return is indicated. The peer group used is the EEI Utilities Index. | | |
Adjustment To PEO Compensation, Footnote [Text Block] | The dollar amounts do not reflect the actual amount of compensation earned or paid during the applicable year. The following adjustments were made to total compensation from the Summary Compensation Table ("SCT") for each year to arrive at compensation actually paid, as computed in accordance with Item 402(v) of Regulation S-K (in dollars). 2022 2021 2020 PEO Average non-PEO NEOs PEO Average non-PEO NEOs PEO PEO Average non-PEO NEOs Less SCT total grant date fair value of equity awards (2,092,631) (475,607) (1,714,845) (515,070) (1,371,935) (2,268,182) (466,880) Less pension value — — (1,760,278) (567,460) (2,711,412) (2,613,893) (1,069,692) Fair value of awards grant during fiscal year that remain unvested at fiscal year end (7) 2,494,680 446,824 2,675,143 803,500 1,293,581 208,203 440,209 Increase by fair value of awards granted during applicable fiscal year that vested during fiscal year, determined at vesting date — 9,960 — — — 86,365 — +/- By Change In Fair Value Of Outstanding Unvested Prior FY Awards That Remain Unvested At FY End Compared To Fair Value As Of Prior FY End (7) (79,170) (17,802) 760,964 301,104 (32,091) 25,610 (17,817) +/- For Awards Granted during Prior FY, determined based on change in ASC 718 Fair Value from Prior FY End to Vesting Date (7) (85,861) (50,052) (73,702) (41,379) 12,945 (72,566) 7,678 Deduction of fair value of prior fiscal year awards as of prior fiscal year end that were forfeited during fiscal year — (73,652) — — — (1,687,333) — Increase by amount of dividends paid on unvested awards during fiscal year prior to vesting date 47,604 11,399 31,852 11,567 19,872 24,108 9,238 Increase by incremental fair value of options/SARS modified during fiscal year — — — — — — — Increase by service cost and prior service cost (if applicable) for pension plans during fiscal year — 257,634 — 327,356 — — 219,276 284,622 108,704 (80,866) 319,618 (2,789,040) (6,297,688) (877,988) | | |
Non-PEO NEO Average Total Compensation Amount | $ 1,326,582 | $ 1,977,637 | $ 2,351,741 |
Non-PEO NEO Average Compensation Actually Paid Amount | $ 1,435,286 | 2,297,255 | 1,473,753 |
Adjustment to Non-PEO NEO Compensation Footnote [Text Block] | The dollar amounts do not reflect the actual amount of compensation earned or paid during the applicable year. The following adjustments were made to total compensation from the Summary Compensation Table ("SCT") for each year to arrive at compensation actually paid, as computed in accordance with Item 402(v) of Regulation S-K (in dollars). 2022 2021 2020 PEO Average non-PEO NEOs PEO Average non-PEO NEOs PEO PEO Average non-PEO NEOs Less SCT total grant date fair value of equity awards (2,092,631) (475,607) (1,714,845) (515,070) (1,371,935) (2,268,182) (466,880) Less pension value — — (1,760,278) (567,460) (2,711,412) (2,613,893) (1,069,692) Fair value of awards grant during fiscal year that remain unvested at fiscal year end (7) 2,494,680 446,824 2,675,143 803,500 1,293,581 208,203 440,209 Increase by fair value of awards granted during applicable fiscal year that vested during fiscal year, determined at vesting date — 9,960 — — — 86,365 — +/- By Change In Fair Value Of Outstanding Unvested Prior FY Awards That Remain Unvested At FY End Compared To Fair Value As Of Prior FY End (7) (79,170) (17,802) 760,964 301,104 (32,091) 25,610 (17,817) +/- For Awards Granted during Prior FY, determined based on change in ASC 718 Fair Value from Prior FY End to Vesting Date (7) (85,861) (50,052) (73,702) (41,379) 12,945 (72,566) 7,678 Deduction of fair value of prior fiscal year awards as of prior fiscal year end that were forfeited during fiscal year — (73,652) — — — (1,687,333) — Increase by amount of dividends paid on unvested awards during fiscal year prior to vesting date 47,604 11,399 31,852 11,567 19,872 24,108 9,238 Increase by incremental fair value of options/SARS modified during fiscal year — — — — — — — Increase by service cost and prior service cost (if applicable) for pension plans during fiscal year — 257,634 — 327,356 — — 219,276 284,622 108,704 (80,866) 319,618 (2,789,040) (6,297,688) (877,988) | | |
Compensation Actually Paid vs. Total Shareholder Return [Text Block] | | | |
Compensation Actually Paid vs. Net Income [Text Block] | | | |
Compensation Actually Paid vs. Company Selected Measure [Text Block] | | | |
Total Shareholder Return Vs Peer Group [Text Block] | | | |
Tabular List [Table Text Block] | As described in more detail under " Compensation Discussion and Analysis ," the most important financial performance measures used by the Company to link compensation actually paid to our NEOs, for the most recently completed fiscal year, to the company's performance are as follows: • CEPS; • TSR; and, • Adjusted consolidated net income. | | |
Total Shareholder Return Amount | $ 110.06 | 112.38 | 92.53 |
Peer Group Total Shareholder Return Amount | 117.09 | 115.76 | 98.84 |
Net Income (Loss) | $ 259,560,000 | $ 245,872,000 | $ 237,968,000 |
Company Selected Measure Amount | 14.65 | 14.15 | 13.79 |
Measure [Axis]: 1 | | | |
Pay vs Performance Disclosure [Table] | | | |
Measure Name | •CEPS | | |
Measure [Axis]: 2 | | | |
Pay vs Performance Disclosure [Table] | | | |
Measure Name | •TSR | | |
Measure [Axis]: 3 | | | |
Pay vs Performance Disclosure [Table] | | | |
Measure Name | •Adjusted consolidated net income | | |
Ms. Grow [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
PEO Total Compensation Amount | $ 4,441,045 | $ 5,645,525 | $ 5,903,347 |
PEO Actually Paid Compensation Amount | $ 4,725,667 | 5,564,659 | 3,114,307 |
PEO Name | Ms. Grow | | |
Mr. Anderson [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
PEO Total Compensation Amount | | | 6,318,341 |
PEO Actually Paid Compensation Amount | | | 20,653 |
PEO [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | $ 284,622 | (80,866) | |
PEO [Member] | Adjustment, Equity Awards Granted During Year [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | (2,092,631) | (1,714,845) | |
PEO [Member] | Adjustment, Change in Pension Value [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | 0 | (1,760,278) | |
PEO [Member] | Adjustment, Equity Awards Granted During Year, Unvested [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | 2,494,680 | 2,675,143 | |
PEO [Member] | Adjustment, Equity Awards Granted During the Year, Vested [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | 0 | 0 | |
PEO [Member] | Adjustment, Equity Awards Granted in Prior Years, Unvested [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | (79,170) | 760,964 | |
PEO [Member] | Adjustment, Equity Awards Granted in Prior Years, Vested [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | (85,861) | (73,702) | |
PEO [Member] | Adjustment, Forfeitures of Prior Year Awards that Failed to Vest During the Year [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | 0 | 0 | |
PEO [Member] | Adjustment, Dividends Paid on Unvested Awards [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | 47,604 | 31,852 | |
PEO [Member] | Adjustment, Options Modified [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | 0 | 0 | |
PEO [Member] | Adjustment, Pension Service Cost [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | 0 | 0 | |
PEO [Member] | Ms. Grow [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | (2,789,040) |
PEO [Member] | Ms. Grow [Member] | Adjustment, Equity Awards Granted During Year [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | (1,371,935) |
PEO [Member] | Ms. Grow [Member] | Adjustment, Change in Pension Value [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | (2,711,412) |
PEO [Member] | Ms. Grow [Member] | Adjustment, Equity Awards Granted During Year, Unvested [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | 1,293,581 |
PEO [Member] | Ms. Grow [Member] | Adjustment, Equity Awards Granted During the Year, Vested [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | 0 |
PEO [Member] | Ms. Grow [Member] | Adjustment, Equity Awards Granted in Prior Years, Unvested [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | (32,091) |
PEO [Member] | Ms. Grow [Member] | Adjustment, Equity Awards Granted in Prior Years, Vested [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | 12,945 |
PEO [Member] | Ms. Grow [Member] | Adjustment, Forfeitures of Prior Year Awards that Failed to Vest During the Year [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | 0 |
PEO [Member] | Ms. Grow [Member] | Adjustment, Dividends Paid on Unvested Awards [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | 19,872 |
PEO [Member] | Ms. Grow [Member] | Adjustment, Options Modified [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | 0 |
PEO [Member] | Ms. Grow [Member] | Adjustment, Pension Service Cost [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | 0 |
PEO [Member] | Mr. Anderson [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | (6,297,688) |
PEO [Member] | Mr. Anderson [Member] | Adjustment, Equity Awards Granted During Year [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | (2,268,182) |
PEO [Member] | Mr. Anderson [Member] | Adjustment, Change in Pension Value [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | (2,613,893) |
PEO [Member] | Mr. Anderson [Member] | Adjustment, Equity Awards Granted During Year, Unvested [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | 208,203 |
PEO [Member] | Mr. Anderson [Member] | Adjustment, Equity Awards Granted During the Year, Vested [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | 86,365 |
PEO [Member] | Mr. Anderson [Member] | Adjustment, Equity Awards Granted in Prior Years, Unvested [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | 25,610 |
PEO [Member] | Mr. Anderson [Member] | Adjustment, Equity Awards Granted in Prior Years, Vested [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | (72,566) |
PEO [Member] | Mr. Anderson [Member] | Adjustment, Forfeitures of Prior Year Awards that Failed to Vest During the Year [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | (1,687,333) |
PEO [Member] | Mr. Anderson [Member] | Adjustment, Dividends Paid on Unvested Awards [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | 24,108 |
PEO [Member] | Mr. Anderson [Member] | Adjustment, Options Modified [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | 0 |
PEO [Member] | Mr. Anderson [Member] | Adjustment, Pension Service Cost [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | | | 0 |
Non-PEO NEO [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | 108,704 | 319,618 | (877,988) |
Non-PEO NEO [Member] | Adjustment, Equity Awards Granted During Year [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | (475,607) | (515,070) | (466,880) |
Non-PEO NEO [Member] | Adjustment, Change in Pension Value [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | 0 | (567,460) | (1,069,692) |
Non-PEO NEO [Member] | Adjustment, Equity Awards Granted During Year, Unvested [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | 446,824 | 803,500 | 440,209 |
Non-PEO NEO [Member] | Adjustment, Equity Awards Granted During the Year, Vested [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | 9,960 | 0 | 0 |
Non-PEO NEO [Member] | Adjustment, Equity Awards Granted in Prior Years, Unvested [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | (17,802) | 301,104 | (17,817) |
Non-PEO NEO [Member] | Adjustment, Equity Awards Granted in Prior Years, Vested [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | (50,052) | (41,379) | 7,678 |
Non-PEO NEO [Member] | Adjustment, Forfeitures of Prior Year Awards that Failed to Vest During the Year [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | (73,652) | 0 | 0 |
Non-PEO NEO [Member] | Adjustment, Dividends Paid on Unvested Awards [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | 11,399 | 11,567 | 9,238 |
Non-PEO NEO [Member] | Adjustment, Options Modified [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | 0 | 0 | 0 |
Non-PEO NEO [Member] | Adjustment, Pension Service Cost [Member] | | | |
Pay vs Performance Disclosure [Table] | | | |
Adjustment to Compensation Amount | $ 257,634 | $ 327,356 | $ 219,276 |