Derivative Instruments (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Cumulative Foreign Currency Translation Gain Loss Recorded In Accumulated Other Comprehensive Income Loss For Net Investment In Foreign Operations Hedges	$ 168	$ 201

Cumulative foreign currency translation gain (loss) recorded in accumulated other comprehensive income (loss) related to hedges of net investments in foreign operations.

No definition available.

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