Investments (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available for Sale Securities
Amortized cost	$ 59,008	$ 71,915
Gross unrealized gains	2,475	5,632
Gross unrealized losses	(573)	(530)
Fair value	60,910	77,017
U.S. government and agencies
Schedule of Available for Sale Securities
Amortized cost	2,791	4,387
Gross unrealized gains	129	326
Gross unrealized losses	(7)
Fair value	2,913	4,713
Municipal
Schedule of Available for Sale Securities
Amortized cost	8,446	12,139
Gross unrealized gains	364	1,038
Gross unrealized losses	(87)	(108)
Fair value	8,723	13,069
Corporate
Schedule of Available for Sale Securities
Amortized cost	39,331	44,943
Gross unrealized gains	1,659	3,721
Gross unrealized losses	(387)	(127)
Fair value	40,603	48,537
Foreign government
Schedule of Available for Sale Securities
Amortized cost	1,736	2,290
Gross unrealized gains	99	228
Gross unrealized losses	(11)	(1)
Fair value	1,824	2,517
ABS
Schedule of Available for Sale Securities
Amortized cost	4,491	3,623
Gross unrealized gains	71	108
Gross unrealized losses	(44)	(107)
Fair value	4,518	3,624
RMBS
Schedule of Available for Sale Securities
Amortized cost	1,403	3,000
Gross unrealized gains	101	142
Gross unrealized losses	(30)	(110)
Fair value	1,474	3,032
CMBS
Schedule of Available for Sale Securities
Amortized cost	788	1,510
Gross unrealized gains	48	65
Gross unrealized losses	(7)	(77)
Fair value	829	1,498
Redeemable preferred stock
Schedule of Available for Sale Securities
Amortized cost	22	23
Gross unrealized gains	4	4
Fair value	$ 26	$ 27