Investments (Details 17) (USD $) In Millions, except Share data, unless otherwise specified	Jun. 30, 2011	Dec. 31, 2010
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Amortized Cost	$ 330,903	$ 317,617
Less than six months [Member] | Less than 20% [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Amortized Cost	26,453	105,301
Cost or Amortized Cost	132	247
Gross Unrealized Loss	367	2,348
Gross Unrealized Loss	6	10
Less than six months [Member] | Less than 20% [Member] | Fixed maturity securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Number of Securities	1,963	5,320
Less than six months [Member] | Less than 20% [Member] | Equity Securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Number of Securities	74	106
Less than six months [Member] | 20% or more [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Amortized Cost	2,874	1,403
Cost or Amortized Cost	8	94
Gross Unrealized Loss	825	368
Gross Unrealized Loss	4	22
Less than six months [Member] | 20% or more [Member] | Fixed maturity securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Number of Securities	167	121
Less than six months [Member] | 20% or more [Member] | Equity Securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Number of Securities	16	33
Six months or greater but less than nine months [Member] | Less than 20% [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Amortized Cost	50,011	1,125
Cost or Amortized Cost	144	29
Gross Unrealized Loss	1,329	29
Gross Unrealized Loss	6	5
Six months or greater but less than nine months [Member] | Less than 20% [Member] | Fixed maturity securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Number of Securities	2,639	104
Six months or greater but less than nine months [Member] | Less than 20% [Member] | Equity Securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Number of Securities	32	3
Six months or greater but less than nine months [Member] | 20% or more [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Amortized Cost	420	376
Cost or Amortized Cost	1	65
Gross Unrealized Loss	104	102
Gross Unrealized Loss	0	16
Six months or greater but less than nine months [Member] | 20% or more [Member] | Fixed maturity securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Number of Securities	31	29
Six months or greater but less than nine months [Member] | 20% or more [Member] | Equity Securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Number of Securities	9	2
Nine months or greater but less than twelve months [Member] | Less than 20% [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Amortized Cost	1,985	371
Cost or Amortized Cost	0	6
Gross Unrealized Loss	130	28
Gross Unrealized Loss	0	0
Nine months or greater but less than twelve months [Member] | Less than 20% [Member] | Fixed maturity securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Number of Securities	260	50
Nine months or greater but less than twelve months [Member] | Less than 20% [Member] | Equity Securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Number of Securities	0	3
Nine months or greater but less than twelve months [Member] | 20% or more [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Amortized Cost	186	89
Cost or Amortized Cost	1	47
Gross Unrealized Loss	64	27
Gross Unrealized Loss	0	16
Nine months or greater but less than twelve months [Member] | 20% or more [Member] | Fixed maturity securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Number of Securities	12	9
Nine months or greater but less than twelve months [Member] | 20% or more [Member] | Equity Securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Number of Securities	4	2
Twelve months or greater [Member] | Less than 20% [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Amortized Cost	16,861	21,627
Cost or Amortized Cost	355	518
Gross Unrealized Loss	1,489	1,863
Gross Unrealized Loss	30	56
Twelve months or greater [Member] | Less than 20% [Member] | Fixed maturity securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Number of Securities	1,025	1,245
Twelve months or greater [Member] | Less than 20% [Member] | Equity Securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Number of Securities	23	35
Twelve months or greater [Member] | 20% or more [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Amortized Cost	3,065	5,546
Cost or Amortized Cost	229	340
Gross Unrealized Loss	1,029	1,815
Gross Unrealized Loss	69	116
Twelve months or greater [Member] | 20% or more [Member] | Fixed maturity securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Number of Securities	196	311
Twelve months or greater [Member] | 20% or more [Member] | Equity Securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Number of Securities	11	14
Less than 20% [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Amortized Cost	95,310	128,424
Cost or Amortized Cost	631	800
Gross Unrealized Loss	3,315	4,268
Gross Unrealized Loss	42	71
Less than 20% [Member] | Fixed maturity securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Gross unrealized loss, percentage of amortized cost fixed maturity securities	3.00%	3.00%
Less than 20% [Member] | Equity Securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Gross unrealized loss, percentage of cost equity securities	7.00%	9.00%
20% or more [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Amortized Cost	6,545	7,414
Cost or Amortized Cost	239	546
Gross Unrealized Loss	2,022	2,312
Gross Unrealized Loss	73	170
20% or more [Member] | Fixed maturity securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Gross unrealized loss, percentage of amortized cost fixed maturity securities	31.00%	31.00%
20% or more [Member] | Equity Securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Gross unrealized loss, percentage of cost equity securities	31.00%	31.00%
Fixed maturity securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Amortized Cost	330,903	317,617
Equity Securities [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Cost or Amortized Cost	$ 3,128	$ 3,621