Fair Value, Assets and Liabilities Measured on Recurring Basis Level 3 Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Trading securities and trading assets, excluding derivatives [Member]
Assets:
Balance, beginning of period	$ 573	$ 897	$ 650	$ 823
Net gains (losses) included in net income	21	8	66	32
Net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	0	(62)	(115)	(38)
Transfers into Level 3	0	0	1	28
Transfers out of Level 3	(83)	(38)	(91)	(40)
Balance, end of period	511	805	511	805
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	14	2	15	4
Trading assets (excluding derivatives) [Member]
Assets:
Balance, beginning of period	509	845	595	769
Net gains (losses) included in net income	22	11	61	37
Net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	1	(62)	(117)	(38)
Transfers into Level 3	0	0	0	28
Transfers out of Level 3	(83)	(38)	(90)	(40)
Balance, end of period	449	756	449	756
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	13	3	6	4
Trading assets (excluding derivatives) [Member] | Securities of U.S. states and political subdivisions [Member]
Assets:
Balance, beginning of period	6	40	7	39
Net gains (losses) included in net income	0	0	0	0
Net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	2	(1)	1	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	(31)	0	(31)
Balance, end of period	8	8	8	8
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	0	0	0	0
Trading assets (excluding derivatives) [Member] | Mortgage-Backed Securities [Member]
Assets:
Balance, beginning of period	0	1	0	1
Net gains (losses) included in net income	0	0	0	0
Net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	0	1	0	1
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	0	0	0	0
Trading assets (excluding derivatives) [Member] | Collateralized loan and other debt obligations [Member]
Assets:
Balance, beginning of period	381	608	445	541
Net gains (losses) included in net income	21	3	42	14
Net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	5	(26)	(80)	26
Transfers into Level 3	0	0	0	4
Transfers out of Level 3	0	(4)	0	(4)
Balance, end of period	407	581	407	581
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	13	(10)	7	(23)
Trading assets (excluding derivatives) [Member] | Corporate debt securities [Member]
Assets:
Balance, beginning of period	31	86	54	53
Net gains (losses) included in net income	0	(4)	2	(3)
Net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	4	(20)	(14)	(11)
Transfers into Level 3	0	0	0	24
Transfers out of Level 3	(2)	0	(9)	(1)
Balance, end of period	33	62	33	62
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	0	1	(1)	1
Trading assets (excluding derivatives) [Member] | Asset-backed securities [Member]
Assets:
Balance, beginning of period	81	97	79	122
Net gains (losses) included in net income	0	12	16	26
Net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	0	(15)	(14)	(53)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	(81)	(3)	(81)	(4)
Balance, end of period	0	91	0	91
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	0	12	0	26
Trading assets (excluding derivatives) [Member] | Equity Securities [Member]
Assets:
Balance, beginning of period	10	13	10	13
Net gains (losses) included in net income	1	0	1	0
Net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	(10)	0	(10)	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	1	13	1	13
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	0	0	0	0
Other trading assets [Member]
Assets:
Balance, beginning of period	64	52	55	54
Net gains (losses) included in net income	(1)	(3)	5	(5)
Net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	(1)	0	2	0
Transfers into Level 3	$ 0	0	1	0
Transfers out of Level 3		0	(1)	0
Balance, end of period	$ 62	49	62	49
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	1	(1)	9	0
Mortgages held for sale [Member]
Assets:
Balance, beginning of period	2,098	2,363	2,313	2,374
Net gains (losses) included in net income	(1)	21	37	23
Net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	(141)	(29)	(369)	(75)
Transfers into Level 3	53	139	95	196
Transfers out of Level 3	(386)	(98)	(453)	(122)
Balance, end of period	1,623	2,396	1,623	2,396
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	(8)	24	6	22
Loans [Member]
Assets:
Balance, beginning of period	5,730	5,689	5,788	5,723
Net gains (losses) included in net income	(41)	3	(47)	5
Net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	(38)	(36)	(90)	(23)
Transfers into Level 3	0	270	0	270
Transfers out of Level 3	0	0	0	(49)
Balance, end of period	5,651	5,926	5,651	5,926
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	(37)	7	(37)	12
Mortgage servicing rights [Member]
Assets:
Balance, beginning of period	11,739	14,953	12,738	15,580
Net gains (losses) included in net income	499	(1,324)	(807)	(2,240)
Net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	423	271	730	560
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	12,661	13,900	12,661	13,900
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	1,053	(835)	280	(1,276)
Derivative [Member]
Assets and Liabilities:
Balance, beginning of period	44	(282)	(23)	(465)
Net gains (losses) included in net income	20	561	484	919
Total net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	(131)	(550)	(482)	(683)
Transfers into Level 3	0	(3)	(12)	0
Transfers out of Level 3	(18)	132	(52)	87
Balance, end of period	(85)	(142)	(85)	(142)
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	59	132	45	281
Derivative [Member] | Interest rate contract [Member]
Assets and Liabilities:
Balance, beginning of period	438	58	293	(40)
Net gains (losses) included in net income	(57)	551	425	913
Total net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	(129)	(426)	(466)	(690)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	252	183	252	183
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	8	199	57	236
Derivative [Member] | Commodity contract [Member]
Assets and Liabilities:
Balance, beginning of period	(2)	(43)	1	(10)
Net gains (losses) included in net income	3	10	2	(21)
Total net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	2	(2)	2	(1)
Transfers into Level 3	0	0	(2)	(3)
Transfers out of Level 3	0	37	0	37
Balance, end of period	3	2	3	2
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	3	0	1	0
Derivative [Member] | Equity contract [Member]
Assets and Liabilities:
Balance, beginning of period	(186)	(24)	(84)	(46)
Net gains (losses) included in net income	57	(3)	50	19
Total net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	(38)	(115)	(89)	(76)
Transfers into Level 3	0	(3)	(10)	3
Transfers out of Level 3	(18)	95	(52)	50
Balance, end of period	(185)	(50)	(185)	(50)
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	43	(50)	(14)	64
Derivative [Member] | Foreign exchange contract [Member]
Assets and Liabilities:
Balance, beginning of period	0	6	0	9
Net gains (losses) included in net income	0	3	0	5
Total net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	0	(7)	0	(12)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	0	2	0	2
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	0	(3)	0	(5)
Derivative [Member] | Credit contract [Member]
Assets and Liabilities:
Balance, beginning of period	(154)	(268)	(189)	(375)
Net gains (losses) included in net income	3	2	1	13
Total net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	34	0	71	96
Transfers into Level 3	$ 0	0	0	0
Transfers out of Level 3		0	0	0
Balance, end of period	$ (117)	(266)	(117)	(266)
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	(9)	(14)	(5)	(14)
Derivative [Member] | Other contract [Member]
Assets and Liabilities:
Balance, beginning of period	(52)	(11)	(44)	(3)
Net gains (losses) included in net income	14	(2)	6	(10)
Total net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	(38)	(13)	(38)	(13)
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	14	0	6	0
Other assets [Member]
Assets:
Balance, beginning of period	2,628	2,040	2,593	1,503
Net gains (losses) included in net income	(7)	(30)	31	(93)
Net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	90	(5)	87	595
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	2,711	2,005	2,711	2,005
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	(8)	(2)	29	(7)
Short sale liabilities [Member]
Liabilities:
Balance, beginning of period	(15)	(5)	(6)	0
Net gains (losses) included in net income	0	1	0	(1)
Net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	14	6	5	1
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	(1)	0	(1)	0
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	0	0	0	0
Other liabilities [Member]
Liabilities:
Balance, beginning of period	(27)	(37)	(28)	(39)
Net gains (losses) included in net income	(3)	(7)	(2)	(7)
Net gains (losses) included in other comprehensive income		0	0	0
Purchases, sales, issuances and settlements, net	0	(1)	0	1
Transfers into Level 3		0	0	0
Transfers out of Level 3		0	0	0
Balance, end of period	(30)	(45)	(30)	(45)
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	0	0	0	(1)
Available-for-sale securities [Member]
Assets:
Balance, beginning of period	5,544	7,260	6,029	7,995
Net gains (losses) included in net income	40	39	77	110
Net gains (losses) included in other comprehensive income	2	(22)	(33)	(29)
Purchases, sales, issuances and settlements, net	(92)	(10)	(527)	(904)
Transfers into Level 3	0	53	0	148
Transfers out of Level 3	(664)	(97)	(716)	(97)
Balance, end of period	4,830	7,223	4,830	7,223
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	2	(5)	(3)	(5)
Available-for-sale securities [Member] | Debt Securities [Member]
Assets:
Balance, beginning of period	4,904	6,552	5,366	7,266
Net gains (losses) included in net income	40	34	74	102
Net gains (losses) included in other comprehensive income	2	(16)	(31)	(19)
Purchases, sales, issuances and settlements, net	(92)	(3)	(503)	(877)
Transfers into Level 3	0	53	0	148
Transfers out of Level 3	(24)	(97)	(76)	(97)
Balance, end of period	4,830	6,523	4,830	6,523
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	2	(5)	(3)	(5)
Available-for-sale securities [Member] | Securities of U.S. states and political subdivisions [Member]
Assets:
Balance, beginning of period	1,980	3,099	2,277	3,214
Net gains (losses) included in net income	4	0	3	9
Net gains (losses) included in other comprehensive income	(12)	7	(15)	9
Purchases, sales, issuances and settlements, net	(59)	107	(300)	(25)
Transfers into Level 3	0	53	0	59
Transfers out of Level 3	(24)	(97)	(76)	(97)
Balance, end of period	1,889	3,169	1,889	3,169
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	0	(2)	(5)	(2)
Available-for-sale securities [Member] | Mortgage-Backed Securities [Member]
Assets:
Balance, beginning of period	104	182	133	202
Net gains (losses) included in net income	0	(2)	5	9
Net gains (losses) included in other comprehensive income	(1)	(2)	(8)	6
Purchases, sales, issuances and settlements, net	0	(1)	(27)	(40)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	103	177	103	177
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	0	(1)	0	(1)
Available-for-sale securities [Member] | Residential [Member]
Assets:
Balance, beginning of period	0	41	24	64
Net gains (losses) included in net income	0	0	4	10
Net gains (losses) included in other comprehensive income	0	1	(6)	(2)
Purchases, sales, issuances and settlements, net	0	(1)	(22)	(31)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	0	41	0	41
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	0	0	0	0
Available-for-sale securities [Member] | Commercial [Member]
Assets:
Balance, beginning of period	104	141	109	138
Net gains (losses) included in net income	0	(2)	1	(1)
Net gains (losses) included in other comprehensive income	(1)	(3)	(2)	8
Purchases, sales, issuances and settlements, net	0	0	(5)	(9)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	103	136	103	136
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	0	(1)	0	(1)
Available-for-sale securities [Member] | Collateralized loan and other debt obligations [Member]
Assets:
Balance, beginning of period	1,053	1,420	1,087	1,420
Net gains (losses) included in net income	32	27	61	70
Net gains (losses) included in other comprehensive income	5	(8)	(11)	(21)
Purchases, sales, issuances and settlements, net	(166)	(113)	(213)	(143)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	924	1,326	924	1,326
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	0	(2)	0	(2)
Available-for-sale securities [Member] | Corporate debt securities [Member]
Assets:
Balance, beginning of period	312	297	252	281
Net gains (losses) included in net income	3	9	3	13
Net gains (losses) included in other comprehensive income	(3)	(12)	(3)	(5)
Purchases, sales, issuances and settlements, net	22	(10)	82	(5)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	334	284	334	284
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	2	0	2	0
Available-for-sale securities [Member] | Asset-backed securities [Member]
Assets:
Balance, beginning of period	1,455	1,554	1,617	2,149
Net gains (losses) included in net income	1	0	2	1
Net gains (losses) included in other comprehensive income	13	(1)	6	(8)
Purchases, sales, issuances and settlements, net	111	14	(45)	(664)
Transfers into Level 3	0	0	0	89
Transfers out of Level 3	0	0	0	0
Balance, end of period	1,580	1,567	1,580	1,567
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	0	0	0	0
Available-for-sale securities [Member] | Auto loans and leases [Member]
Assets:
Balance, beginning of period	249	274	245	492
Net gains (losses) included in net income	0	0	0	0
Net gains (losses) included in other comprehensive income	11	(2)	15	(5)
Purchases, sales, issuances and settlements, net	0	0	0	(215)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	260	272	260	272
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	0	0	0	0
Available-for-sale securities [Member] | Other asset-backed securities [Member]
Assets:
Balance, beginning of period	1,206	1,280	1,372	1,657
Net gains (losses) included in net income	1	0	2	1
Net gains (losses) included in other comprehensive income	2	1	(9)	(3)
Purchases, sales, issuances and settlements, net	111	14	(45)	(449)
Transfers into Level 3	0	0	0	89
Transfers out of Level 3	0	0	0	0
Balance, end of period	1,320	1,295	1,320	1,295
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	0	0	0	0
Available-for-sale securities [Member] | Equity Securities [Member]
Assets:
Balance, beginning of period	640	708	663	729
Net gains (losses) included in net income	0	5	3	8
Net gains (losses) included in other comprehensive income	0	(6)	(2)	(10)
Purchases, sales, issuances and settlements, net	0	(7)	(24)	(27)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	(640)	0	(640)	0
Balance, end of period	0	700	0	700
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	0	0	0	0
Available-for-sale securities [Member] | Perpetual preferred securities [Member]
Assets:
Balance, beginning of period	640	708	663	729
Net gains (losses) included in net income	0	1	3	4
Net gains (losses) included in other comprehensive income	0	(6)	(2)	(10)
Purchases, sales, issuances and settlements, net	0	(3)	(24)	(23)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	(640)	0	(640)	0
Balance, end of period	0	700	0	700
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	0	0	0	0
Available-for-sale securities [Member] | Other marketable equity securities [Member]
Assets:
Balance, beginning of period	0	0	0	0
Net gains (losses) included in net income	0	4	0	4
Net gains (losses) included in other comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	0	(4)	0	(4)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	0	0	0	0
Net unrealized gains (losses) included in income related to assets and liabilities held at period end	$ 0	$ 0	$ 0	$ 0