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		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		$ (841)	$ (839)	$ (929)	$ (741)
Gains (losses) included in shareholders' net income:
GMIB fair value gain/(loss)		(104)	(33)	(37)	(163)
Other		0	2	2	12
Total gains (losses) included in shareholders' net income		(104)	(31)	(35)	(151)
Gains (losses) included in other comprehensive income		0	0	0	0
Gains (losses) required to adjust future policy benefits for settlement annuities	[1]	0	0	0	0
Purchases, issuances, settlements:
Purchases		0	0	0	0
Sales		0	0	0	0
Settlements		10	13	29	35
Total purchases, sales, and settlements		10	13	29	35
Transfers into/(out of) Level 3:
Transfers into Level 3		0	0	0	0
Transfers out of Level 3		0	0	0	0
Transfers into/(out of) Level 3		0	0	0	0
Ending balance		(935)	(857)	(935)	(857)
Total gains (losses) included in income attributable to instruments held at the reporting date		$ (104)	$ (31)	$ (35)	$ (151)

[1] Amounts do not accrue to shareholders.