Financial Condition and Net Income on a Statutory Basis - Significant Subsidiaries (Reconciliation of NAIC SAP and Prescribed Practice) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Statutory Basis [Abstract]
Prescribed Practice Surplus Note	$ 652	$ 624
Prescribed Practice Letters Of Credit	(576)	(976)
Surplus Deficit NAIC SAP	$ 76	$ (352)

Represents surplus of the reporting company, including accrued surplus note interest that is reported as a reduction in surplus under prescribed practices but not under NAIC SAP.

No definition available.

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