Investments (Changes in Net Unrealized Investment Gains (Losses)) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2019 USD ($)
Investments, Debt and Equity Securities [Abstract]
Balance, December 31, 2018	$ 744
Unrealized investment gains (losses) during the period	4,098
Unrealized investment gains (losses) relating to:
Future policy benefits	(1,432)
DAC, VOBA and DSI	(199)
Deferred income tax benefit (expense)	(518)
Balance, June 30, 2019	2,693
Change in net unrealized investment gains (losses)	$ 1,949