Fair Value, Assets and Liabilities, Changes in Level 3 Fair Value Assets and Liabilities on a Recurring Basis (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Trading debt securities [Member]
Assets:
Balance, beginning of period	$ 241	$ 173
Net gains (losses)	(15)	16
Purchases	47	169
Sales	(14)	(173)
Settlements	(35)	0
Transfers into Level 3	5	7
Transfers out of Level 3	(28)	0
Balance, end of period	201	192
Net unrealized gains (losses) related to assets and liabilities held at period end	(17)	8
Available-for-sale debt securities [Member]
Assets:
Balance, beginning of period	186	2,994
Net gains (losses)	(21)	(7)
Purchases	52	15
Sales	0	0
Settlements	(5)	(68)
Transfers into Level 3	126	242
Transfers out of Level 3	0	(34)
Balance, end of period	338	3,142
Net unrealized gains (losses) related to assets and liabilities held at period end	(21)	(27)
Fair Value Disclosures, Textual [Abstract]
Total net gains (losses) included in other comprehensive income	(21)	14
Net unrealized gains (losses) related to assets and liabilities held at period end and included in other comprehensive income	(21)	0
Loans held for sale [Member]
Assets:
Balance, beginning of period	1,033	1,234
Net gains (losses)	(57)	(19)
Purchases	63	129
Sales	(43)	(148)
Settlements	(73)	(110)
Transfers into Level 3	102	81
Transfers out of Level 3	(6)	(1)
Balance, end of period	1,019	1,166
Net unrealized gains (losses) related to assets and liabilities held at period end	(57)	(17)
Mortgage servicing rights [Member] | Residential mortgage [Member]
Assets:
Balance, beginning of period	6,920	6,125
Net gains (losses)	1,248	1,006
Purchases	342	406
Sales	1	(1)
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance, end of period	8,511	7,536
Net unrealized gains (losses) related to assets and liabilities held at period end	1,605	1,591
Derivative [Member]
Assets and Liabilities:
Balance, beginning of period	(297)	171
Net gains (losses)	(813)	(682)
Purchases	0	0
Sales	0	0
Settlements	908	131
Transfers into Level 3	(80)	(27)
Transfers out of Level 3	(1,292)	35
Balance, end of period	(1,574)	(372)
Net unrealized gains (losses) related to assets and liabilities held at period end	28	(386)
Derivative [Member] | Interest rate contracts [Member]
Assets and Liabilities:
Balance, beginning of period	127	446
Net gains (losses)	(578)	(541)
Purchases	0	0
Sales	0	0
Settlements	275	101
Transfers into Level 3	0	0
Transfers out of Level 3	0	(5)
Balance, end of period	(176)	1
Net unrealized gains (losses) related to assets and liabilities held at period end	(259)	(225)
Derivative [Member] | Equity contracts [Member]
Assets and Liabilities:
Balance, beginning of period	(429)	(314)
Net gains (losses)	(213)	(168)
Purchases	0	0
Sales	0	0
Settlements	589	40
Transfers into Level 3	(80)	(27)
Transfers out of Level 3	(1,292)	40
Balance, end of period	(1,425)	(429)
Net unrealized gains (losses) related to assets and liabilities held at period end	269	(177)
Derivative [Member] | Equity contracts [Member] | Nonmarketable equity securities [Member]
Assets and Liabilities:
Transfers out of Level 3	1,400
Derivative [Member] | Other contract [Member]
Assets and Liabilities:
Balance, beginning of period	5	39
Net gains (losses)	(22)	27
Purchases	0	0
Sales	0	0
Settlements	44	(10)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance, end of period	27	56
Net unrealized gains (losses) related to assets and liabilities held at period end	18	16
Securities [Member] | Equity securities [Member]
Assets:
Balance, beginning of period	8,910	9,233
Net gains (losses)	(1)	(365)
Purchases	0	0
Sales	0	(5)
Settlements	0	0
Transfers into Level 3	2	2
Transfers out of Level 3	(8,885)	0
Balance, end of period	26	8,865
Net unrealized gains (losses) related to assets and liabilities held at period end	(2)	$ (365)
Securities [Member] | Equity contracts [Member] | Nonmarketable equity securities [Member]
Assets and Liabilities:
Transfers out of Level 3	$ 8,900