Financial Condition and Net Income on a Statutory Basis - Significant Subsidiaries (Reconciliation of NAIC SAP and Prescribed Practice) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statutory Basis [Abstract]
Prescribed Practice Surplus Note	$ 726,531	$ 574,574
Prescribed Practice Letters Of Credit	(960,100)	(615,100)
Surplus Deficit NAIC SAP	$ (233,569)	$ (40,526)

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