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

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