Commitments, Contingencies and Guarantees (Narrative) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Liability For Expected Credit Losses Included in Other Liabilities	$ 1	$ 2

Liability For Expected Credit Losses Included in Other Liabilities, associated with unfunded commitments.

No definition available.

Name:	rga_LiabilityForExpectedCreditLossesIncludedinOtherLiabilities
Namespace Prefix:	rga_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant