Investments (details) - OTTI Rollforward (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Cumulative amount of and the changes during the reporting period in the credit losses of other-than-temporary impairments (OTTI) on fixed maturities recognized in the consolidated statement of income for which a portion of the OTTI was recognized in other comprehensive income [Roll Forward]
Cumulative OTTI credit losses recognized for securities held, beginning of period	$ 109	$ 125	$ 118	$ 127
Additions for OTTI securities where credit losses have been previously recognized			4	2
Reductions due to sales/defaults of credit-impaired securities	(5)		(8)
Adjustments to book value of credit-impaired securities due to changes in cash flows	1	(3)	(9)	(7)
Cumulative OTTI credit losses recognized for securities still held, end of period	105	122	105	122
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Cumulative amount of and the changes during the reporting period in the credit losses of other-than-temporary impairments (OTTI) on fixed maturities recognized in the consolidated statement of income for which a portion of the OTTI was recognized in other comprehensive income [Roll Forward]
Cumulative OTTI credit losses recognized for securities held, beginning of period	43	55	53	55
Additions for OTTI securities where credit losses have been previously recognized			1	2
Reductions due to sales/defaults of credit-impaired securities			(3)
Adjustments to book value of credit-impaired securities due to changes in cash flows	1	(2)	(7)	(4)
Cumulative OTTI credit losses recognized for securities still held, end of period	44	53	44	53
All other corporate bonds [Member]
Cumulative amount of and the changes during the reporting period in the credit losses of other-than-temporary impairments (OTTI) on fixed maturities recognized in the consolidated statement of income for which a portion of the OTTI was recognized in other comprehensive income [Roll Forward]
Cumulative OTTI credit losses recognized for securities held, beginning of period	66	70	65	72
Additions for OTTI securities where credit losses have been previously recognized			3
Reductions due to sales/defaults of credit-impaired securities	(5)		(5)
Adjustments to book value of credit-impaired securities due to changes in cash flows		(1)	(2)	(3)
Cumulative OTTI credit losses recognized for securities still held, end of period	$ 61	$ 69	$ 61	$ 69