DAC, VOBA, DSI, and DFEL (DFEL) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Changes in DFEL [Abstract]
Balance as of beginning-of-year	$ 1,874	$ 1,952	$ 1,401
Deferrals	755	631	539
Amortization, net of interest:
Amortization, excluding unlocking, net of interest	(396)	(365)	(308)
Unlocking	1	(63)	(68)
Adjustment related to realized (gains) losses	(14)	(3)	(4)
Adjustment related to unrealized (gains) losses	(775)	(278)	392
Balance as of end-of-year	$ 1,445	$ 1,874	$ 1,952