Fair Value Measurements - Changes in Level 3 Financial Liabilities (Details) - Derivative Financial Instruments, Liabilities [Member] - Guaranteed Minimum Income Benefit [Member] - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		$ (885)	$ (929)
Gains (losses) included in shareholders' net income:
GMIB fair value gain/(loss)		47	2
Other		(3)	0
Total gains (losses) included in shareholders' net income		44	2
Gains (losses) included in other comprehensive income		0	0
Gains (losses) required to adjust future policy benefits for settlement annuities	[1]	0	0
Purchases, sales, settlements:
Purchases		0	0
Sales		0	0
Settlements		61	42
Total purchases, sales, and settlements		61	42
Transfers into/(out of) Level 3:
Transfers into Level 3		0	0
Transfers out of Level 3		0	0
Transfers into/(out of) Level 3		0	0
Ending balance		(780)	(885)
Total gains (losses) included in income attributable to instruments held at the reporting date		$ 44	$ 2

[1] Amounts do not accrue to shareholders.