Fair Value Measurements (Changes in Level 3 Instruments) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Changes in Level 3 Instruments
Changes in Level 3, beginning balance			$ 2,816
Changes in Level 3, ending balance	2,947		2,947
Cash Accruals Not Included In Schedule Assets Measured For Fair Value On Recurring Basis	12	8	12	8
US Corporate
Changes in Level 3 Instruments
Changes in Level 3, beginning balance	3,155	3,229	2,953	3,591
Net realized/unrealized gains (losses) included in earnings	7	24	27	(247)
Net realized/unrealized gains (losses) included in accumulated other comprehensive income	(9)	(32)	103	184
Purchases	102	160	449	257
Sales	(63)	(34)	(222)	(383)
Settlements	(91)	(49)	(230)	(139)
Transfers into Level 3	32	0	170	108
Transfers out of Level 3	(16)	0	(133)	(73)
Changes in Level 3, ending balance	3,117	3,298	3,117	3,298
Net change in unrealized gains (losses) relating to instruments still held	0	0	0	0
State and municipal
Changes in Level 3 Instruments
Changes in Level 3, beginning balance	560	98	96	77
Net realized/unrealized gains (losses) included in earnings	0	0	0	0
Net realized/unrealized gains (losses) included in accumulated other comprehensive income	0	(4)	31	(8)
Purchases	4	4	17	20
Sales	(10)	0	(17)	0
Settlements	(1)	(4)	(9)	(5)
Transfers into Level 3	19	0	454	10
Transfers out of Level 3	0	0	0	0
Changes in Level 3, ending balance	572	94	572	94
Net change in unrealized gains (losses) relating to instruments still held	0	0	0	0
Residential Mortgage Backed Securities
Changes in Level 3 Instruments
Changes in Level 3, beginning balance	66	91	86	100
Net realized/unrealized gains (losses) included in earnings	0	0	1	0
Net realized/unrealized gains (losses) included in accumulated other comprehensive income	0	(2)	0	(4)
Purchases	0	0	0	0
Sales	0	0	(16)	(2)
Settlements	(3)	(1)	(8)	(6)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	(47)	0	(47)	0
Changes in Level 3, ending balance	16	88	16	88
Net change in unrealized gains (losses) relating to instruments still held	0	0	0	0
Commercial mortgage backed
Changes in Level 3 Instruments
Changes in Level 3, beginning balance	12	5	10	6
Net realized/unrealized gains (losses) included in earnings	0	0	0	0
Net realized/unrealized gains (losses) included in accumulated other comprehensive income	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	(2)	(1)	(2)	(2)
Transfers into Level 3	0	10	2	10
Transfers out of Level 3	0	0	0	0
Changes in Level 3, ending balance	10	14	10	14
Net change in unrealized gains (losses) relating to instruments still held	0	0	0	0
Asset-backed
Changes in Level 3 Instruments
Changes in Level 3, beginning balance	7,277	5,346	6,898	5,023
Net realized/unrealized gains (losses) included in earnings	1	1	3	3
Net realized/unrealized gains (losses) included in accumulated other comprehensive income	(106)	36	(132)	(32)
Purchases	784	569	1,780	1,479
Sales	0	0	0	(1)
Settlements	(689)	(14)	(1,272)	(539)
Transfers into Level 3	0	0	0	12
Transfers out of Level 3	0	0	(10)	(7)
Changes in Level 3, ending balance	7,267	5,938	7,267	5,938
Net change in unrealized gains (losses) relating to instruments still held	0	0	0	0
Corporate - non-U.S.
Changes in Level 3 Instruments
Changes in Level 3, beginning balance	1,054	1,197	1,064	1,218
Net realized/unrealized gains (losses) included in earnings	6	(29)	9	(112)
Net realized/unrealized gains (losses) included in accumulated other comprehensive income	(18)	(2)	61	18
Purchases	179	1,827	614	4,637
Sales	(10)	0	(75)	(3)
Settlements	(208)	(1,930)	(665)	(4,672)
Transfers into Level 3	0	0	1	21
Transfers out of Level 3	0	(10)	(6)	(54)
Changes in Level 3, ending balance	1,003	1,053	1,003	1,053
Net change in unrealized gains (losses) relating to instruments still held	0	0	0	0
Government - non-U.S.
Changes in Level 3 Instruments
Changes in Level 3, beginning balance	1	38	31	42
Net realized/unrealized gains (losses) included in earnings	0	1	0	1
Net realized/unrealized gains (losses) included in accumulated other comprehensive income	0	(6)	0	(10)
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	(1)	0	(31)	0
Changes in Level 3, ending balance	0	33	0	33
Net change in unrealized gains (losses) relating to instruments still held	0	0	0	0
U.S. Government and federal agency
Changes in Level 3 Instruments
Changes in Level 3, beginning balance	249	264	225	277
Net realized/unrealized gains (losses) included in earnings	0	0	0	0
Net realized/unrealized gains (losses) included in accumulated other comprehensive income	6	(52)	32	(65)
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	0	0
Transfers into Level 3	9	0	9	0
Transfers out of Level 3	0	0	(2)	0
Changes in Level 3, ending balance	264	212	264	212
Net change in unrealized gains (losses) relating to instruments still held	0	0	0	0
Retained interest
Changes in Level 3 Instruments
Changes in Level 3, beginning balance	73	93	72	83
Net realized/unrealized gains (losses) included in earnings	32	0	35	5
Net realized/unrealized gains (losses) included in accumulated other comprehensive income	(10)	(11)	(5)	5
Purchases	0	0	1	2
Sales	(67)	0	(67)	0
Settlements	(1)	(4)	(9)	(17)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Changes in Level 3, ending balance	27	78	27	78
Net change in unrealized gains (losses) relating to instruments still held	0	0	0	0
Available-for-sale Securities
Changes in Level 3 Instruments
Changes in Level 3, beginning balance	9	10	11	13
Net realized/unrealized gains (losses) included in earnings	0	0	0	0
Net realized/unrealized gains (losses) included in accumulated other comprehensive income	0	0	0	0
Purchases	0	0	2	0
Sales	0	0	(2)	0
Settlements	0	0	(2)	0
Transfers into Level 3	0	1	0	0
Transfers out of Level 3	0	0	0	(2)
Changes in Level 3, ending balance	9	11	9	11
Net change in unrealized gains (losses) relating to instruments still held	0	0	0	0
Derivatives
Changes in Level 3 Instruments
Changes in Level 3, beginning balance	151	167	164	416
Net realized/unrealized gains (losses) included in earnings	(13)	1	(25)	(52)
Net realized/unrealized gains (losses) included in accumulated other comprehensive income	1	1	1	2
Purchases	(3)	(1)	(4)	(2)
Sales	0	0	0	0
Settlements	(1)	2	1	(221)
Transfers into Level 3	0	2	(1)	28
Transfers out of Level 3	(1)	(1)	(2)	0
Changes in Level 3, ending balance	134	171	134	171
Net change in unrealized gains (losses) relating to instruments still held	15	(13)	19	30
Other 1 [Member]
Changes in Level 3 Instruments
Changes in Level 3, beginning balance	357	854	494	799
Net realized/unrealized gains (losses) included in earnings	3	16	17	(81)
Net realized/unrealized gains (losses) included in accumulated other comprehensive income	0	(1)	0	3
Purchases	266	148	523	352
Sales	(1)	(295)	(16)	(351)
Settlements	(280)	0	(392)	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	2	(4)	(279)	(4)
Changes in Level 3, ending balance	347	718	347	718
Net change in unrealized gains (losses) relating to instruments still held	0	34	(4)	121
Total
Changes in Level 3 Instruments
Changes in Level 3, beginning balance	12,964	11,392	12,104	11,645
Net realized/unrealized gains (losses) included in earnings	36	14	67	(483)
Net realized/unrealized gains (losses) included in accumulated other comprehensive income	(136)	(73)	91	93
Purchases	1,332	2,707	3,382	6,745
Sales	(151)	(329)	(415)	(740)
Settlements	(1,276)	(2,001)	(2,588)	(5,601)
Transfers into Level 3	60	13	635	189
Transfers out of Level 3	(63)	(15)	(510)	(140)
Changes in Level 3, ending balance	12,766	11,708	12,766	11,708
Net change in unrealized gains (losses) relating to instruments still held	$ 15	$ 21	$ 15	$ 151