Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Narrative) (Details)	Sep. 30, 2017	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Percentage Of Fixed Maturity Securities Classified As Level 3	5.90%	6.90%

Percentage of fixed maturity securities classified as Level 3

No definition available.

Name:	rga_PercentageOfFixedMaturitySecuritiesClassifiedAsLevel3
Namespace Prefix:	rga_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant