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		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		$ (948)	$ (794)	$ (929)	$ (741)
Gains (losses) included in shareholders' net income:
GMIB fair value gain/(loss)		94	(53)	67	(130)
Other		3	(2)	2	10
Total gains (losses) included in shareholders' net income		97	(55)	69	(120)
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	10	19	22
Total purchases, sales, and settlements		10	10	19	22
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		(841)	(839)	(841)	(839)
Total gains (losses) included in income attributable to instruments held at the reporting date		$ 97	$ (55)	$ 69	$ (120)

[1] Amounts do not accrue to shareholders.