| Document and Entity Information | May 20, 2020 |
| Document And Entity Information [Line Items] | |
| Entity Registrant Name | REINSURANCE GROUP OF AMERICA INC |
| Amendment Flag | false |
| Entity Central Index Key | 0000898174 |
| Current Fiscal Year End Date | --12-31 |
| Document Type | 8-K |
| Document Period End Date | May 20, 2020 |
| Entity Incorporation State Country Code | MO |
| Entity File Number | 1-11848 |
| Entity Tax Identification Number | 43-1627032 |
| Entity Address, Address Line One | 16600 Swingley Ridge Road |
| Entity Address, City or Town | Chesterfield |
| Entity Address, State or Province | MO |
| Entity Address, Postal Zip Code | 63017 |
| City Area Code | (636) |
| Local Phone Number | 736-7000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Common Stock Outstanding [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Common Stock, par value $0.01 |
| Trading Symbol | RGA |
| Security Exchange Name | NYSE |
| M 6.20 Fixed To Floating Rate Subordinated Debentures Due 2042 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 6.20% Fixed-To-Floating Rate Subordinated Debentures due 2042 |
| Trading Symbol | RZA |
| Security Exchange Name | NYSE |
| M 5.75 Fixed To Floating Rate Subordinated Debentures Due 2056 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 5.75% Fixed-To-Floating Rate Subordinated Debentures due 2056 |
| Trading Symbol | RZB |
| Security Exchange Name | NYSE |
