Fair Value Measurements - Changes in Level 3 Financial Liabilities (Details) - Derivative Financial Instruments, Liabilities [Member] - Guaranteed Minimum Income Benefit [Member] - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 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)		(61)	(27)
Other		(5)	(1)
Total gains (losses) included in shareholders' net income		(66)	(28)
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		10	9
Total purchases, sales, and settlements		10	9
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		(941)	(948)
Total gains (losses) included in income attributable to instruments held at the reporting date		$ (66)	$ (28)

[1] Amounts do not accrue to shareholders.