Income Tax (Details 5) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Valuation Allowance [Line Items]
Income tax expense (benefit)	$ (695)	$ 2,380	$ 765
Deferred income tax expense (benefit) related to unrealized investment gains (losses)	3,279	2,936	2,283
Investments in Foreign Subsidiaries and Foreign Corporate Joint Ventures that are Essentially Permanent in Duration [Member]
Valuation Allowance [Line Items]
Balance, beginning of period	720
Income tax expense (benefit)	32
Deferred income tax expense (benefit) related to unrealized investment gains (losses)	249
Offsetting reduction in gross deferred tax asset related to the branch transfer to subsidiary	(976)
Balance, end of period	25
Investments in Foreign Subsidiaries and Foreign Corporate Joint Ventures that are Essentially Permanent in Duration [Member] | Japan [Member]
Valuation Allowance [Line Items]
Balance, beginning of period	566
Income tax expense (benefit)	(1)
Deferred income tax expense (benefit) related to unrealized investment gains (losses)	320
Offsetting reduction in gross deferred tax asset related to the branch transfer to subsidiary	(885)
Balance, end of period	0
Investments in Foreign Subsidiaries and Foreign Corporate Joint Ventures that are Essentially Permanent in Duration [Member] | U.K. [Member]
Valuation Allowance [Line Items]
Balance, beginning of period	3
Income tax expense (benefit)	55
Deferred income tax expense (benefit) related to unrealized investment gains (losses)	(11)
Offsetting reduction in gross deferred tax asset related to the branch transfer to subsidiary	(47)
Balance, end of period	0
Investments in Foreign Subsidiaries and Foreign Corporate Joint Ventures that are Essentially Permanent in Duration [Member] | Greece [Member]
Valuation Allowance [Line Items]
Balance, beginning of period	128
Income tax expense (benefit)	(34)
Deferred income tax expense (benefit) related to unrealized investment gains (losses)	(50)
Offsetting reduction in gross deferred tax asset related to the branch transfer to subsidiary	(44)
Balance, end of period	0
Investments in Foreign Subsidiaries and Foreign Corporate Joint Ventures that are Essentially Permanent in Duration [Member] | Other Non-U.S. Branches [Member]
Valuation Allowance [Line Items]
Balance, beginning of period	23
Income tax expense (benefit)	12
Deferred income tax expense (benefit) related to unrealized investment gains (losses)	(10)
Offsetting reduction in gross deferred tax asset related to the branch transfer to subsidiary	0
Balance, end of period	$ 25