DAC, VOBA, DSI, and DFEL (DAC) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Changes in DAC [Roll Forward]
Balance as of beginning-of-year	$ 8,617	$ 7,558	$ 7,695
Business acquired (sold) through reinsurance		38
Deferrals	1,344	1,490	1,537
Amortization, net of interest:
Amortization, excluding unlocking, net of interest	(981)	(879)	(988)
Unlocking	(276)	(238)	17
Adjustment related to realized (gains) losses	22	(15)	(31)
Adjustment related to unrealized (gains) losses	(483)	663	(672)
Balance as of end-of-year	$ 8,243	$ 8,617	$ 7,558