Financial Condition and Net Income on a Statutory Basis - Significant Subsidiaries (Statutory Accounting Practices Disclosure) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
RGA Reinsurance [Member]
Statutory Accounting Practices [Line Items]
Statutory Accounting Practices, Statutory Capital and Surplus, Balance	$ 2,150	$ 2,079
Statutory Accounting Practices, Statutory Net Income Amount	280	660	$ 138
RCM [Member]
Statutory Accounting Practices [Line Items]
Statutory Accounting Practices, Statutory Capital and Surplus, Balance	2,125	2,053
Statutory Accounting Practices, Statutory Net Income Amount	75	(25)	(183)
RGA Canada [Member]
Statutory Accounting Practices [Line Items]
Statutory Accounting Practices, Statutory Capital and Surplus, Balance	713	897
Statutory Accounting Practices, Statutory Net Income Amount	(225)	(38)	26
RGA Barbados [Member]
Statutory Accounting Practices [Line Items]
Statutory Accounting Practices, Statutory Capital and Surplus, Balance	1,553	1,170
Statutory Accounting Practices, Statutory Net Income Amount	234	49	309
RGA Australia [Member]
Statutory Accounting Practices [Line Items]
Statutory Accounting Practices, Statutory Capital and Surplus, Balance	447	433
Statutory Accounting Practices, Statutory Net Income Amount	15	(37)	78
RGA Atlantic [Member]
Statutory Accounting Practices [Line Items]
Statutory Accounting Practices, Statutory Capital and Surplus, Balance	1,511	1,083
Statutory Accounting Practices, Statutory Net Income Amount	243	256	214
RGA International Reinsurance Company dac [Member]
Statutory Accounting Practices [Line Items]
Statutory Accounting Practices, Statutory Capital and Surplus, Balance	1,087	691
Statutory Accounting Practices, Statutory Net Income Amount	37	21	23
RGA Americas [Member]
Statutory Accounting Practices [Line Items]
Statutory Accounting Practices, Statutory Capital and Surplus, Balance	6,283	4,298
Statutory Accounting Practices, Statutory Net Income Amount	1,049	209	624
Other Reinsurance Subsidiaries [Member]
Statutory Accounting Practices [Line Items]
Statutory Accounting Practices, Statutory Capital and Surplus, Balance	2,233	1,881
Statutory Accounting Practices, Statutory Net Income Amount	$ 291	$ 324	$ 43