Derivatives Derivatives (Embedded Derivatives - Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Nonperformance Risk [Member] \| Direct And Assumed Guaranteed Minimum Benefit [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Embedded Derivatives Gains (Losses)	$ (173)	$ (15)

Net Increase or Decrease in the fair value of the embedded derivative or group of embedded derivatives included in earnings in the period.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 15
-URI http://asc.fasb.org/subtopic&trid=2229187

Name:	us-gaap_EmbeddedDerivativeGainLossOnEmbeddedDerivativeNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration