| Document and Entity Information | Jan. 14, 2020 |
| Cover [Abstract] | |
| Entity Registrant Name | ENCANA CORP |
| Amendment Flag | false |
| Entity Central Index Key | 0001157806 |
| Document Type | 8-K |
| Document Period End Date | Jan. 14, 2020 |
| Entity Incorporation State Country Code | Z4 |
| Entity File Number | 1-15226 |
| Entity Tax Identification Number | 98-0355077 |
| Entity Address, Address Line One | Suite 4400 |
| Entity Address, Address Line Two | 500 Centre Street SE |
| Entity Address, Address Line Three | PO Box 2850 |
| Entity Address, City or Town | Calgary |
| Entity Address, State or Province | AB |
| Entity Address, Country | CA |
| Entity Address, Postal Zip Code | T2P 2S5 |
| City Area Code | (403) |
| Local Phone Number | 645-2000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Shares |
| Trading Symbol | ECA |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
