Fair Value (Reconciliation of Recurring Fair Value Measurements) (Details) - Fair Value, Measurements, Recurring - Level 3 - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 5,137	$ 5,395
Included in Earnings	1,147	(255)
Included in Other comprehensive income (b)	8	(94)
Purchases	1,207	781
Sales	(1,143)	(231)
Issuances	174	145
Settlements	(1,218)	(612)
Transfers into Level 3	18	112
Transfers out of Level 3	(36)	(104)
Impact from BBVA Acquisition	588
Ending Balance	5,882	5,137
Unrealized gains (losses) on assets held on Consolidated Balance Sheet	847	(301)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	318	344
Included in Earnings	296	206
Purchases
Sales	6	4
Issuances	326	124
Settlements	(490)	(360)
Impact from BBVA Acquisition	7
Ending Balance	463	318
Unrealized gains or (losses) on liabilities held on Consolidated Balance Sheet	269	187
Fair Value Additional Information [Abstract]
Net gains (losses) included in earnings (realized and unrealized) relating to Level 3 assets and liabilities	851	(461)
Net unrealized gains (losses) relating to Level 3 assets and liabilities	578	(488)
Loans Held For Sale \| Residential Mortgages
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	163	2
Included in Earnings	(1)	(1)
Purchases	47	124
Sales	(83)	(13)
Settlements	(41)	(21)
Transfers into Level 3	18	93
Transfers out of Level 3	(22)	(21)
Ending Balance	81	163
Unrealized gains (losses) on assets held on Consolidated Balance Sheet	(1)	(1)
Loans Held For Sale \| Commercial Mortgages
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	57	64
Included in Earnings		(2)
Sales	(6)
Settlements	(2)	(5)
Ending Balance	49	57
Unrealized gains (losses) on assets held on Consolidated Balance Sheet	(1)	(2)
Loans Held For Sale \| Other consumer loans held for sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Sales	(256)
Impact from BBVA Acquisition	256
Securities available for sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	1,647	2,055
Included in Earnings	39	60
Included in Other comprehensive income (b)	8	(94)
Purchases	6	4
Sales
Settlements	(368)	(397)
Transfers into Level 3		19
Ending Balance	1,332	1,647
Securities available for sale \| Residential mortgage-backed Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	1,365	1,741
Included in Earnings	37	53
Included in Other comprehensive income (b)	6	(75)
Settlements	(311)	(354)
Ending Balance	1,097	1,365
Securities available for sale \| Commercial mortgage- backed non-agency
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	11
Included in Other comprehensive income (b)	(8)	(8)
Transfers into Level 3		19
Ending Balance	3	11
Securities available for sale \| Asset-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	199	240
Included in Earnings	2	6
Included in Other comprehensive income (b)	9	(7)
Settlements	(47)	(40)
Ending Balance	163	199
Securities available for sale \| Other debt
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	72	74
Included in Earnings		1
Included in Other comprehensive income (b)	1	(4)
Purchases	6	4
Settlements	(10)	(3)
Ending Balance	69	72
Loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	647	300
Included in Earnings	45	28
Purchases	124	161
Sales	(15)	(39)
Settlements	(194)	280
Transfers out of Level 3	(14)	(83)
Impact from BBVA Acquisition	291
Ending Balance	884	647
Unrealized gains (losses) on assets held on Consolidated Balance Sheet	44	28
Equity investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	1,263	1,276
Included in Earnings	627	(63)
Purchases	573	229
Sales	(783)	(179)
Ending Balance	1,680	1,263
Unrealized gains (losses) on assets held on Consolidated Balance Sheet	338	(69)
Mortgage Servicing Rights \| Residential Mortgages
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	673	995
Included in Earnings	192	(377)
Purchases	411	208
Issuances	87	45
Settlements	(320)	(198)
Impact from BBVA Acquisition	35
Ending Balance	1,078	673
Unrealized gains (losses) on assets held on Consolidated Balance Sheet	192	(377)
Mortgage Servicing Rights \| Commercial Mortgages
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	569	649
Included in Earnings	162	(109)
Purchases	41	44
Issuances	87	100
Settlements	(119)	(115)
Ending Balance	740	569
Unrealized gains (losses) on assets held on Consolidated Balance Sheet	162	(109)
Financial derivatives
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	118	54
Included in Earnings	83	209
Purchases	5	11
Settlements	(174)	(156)
Impact from BBVA Acquisition	6
Ending Balance	38	118
Unrealized gains (losses) on assets held on Consolidated Balance Sheet	113	229
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	273	200
Included in Earnings	145	189
Sales	6	4
Settlements	(146)	(120)
Impact from BBVA Acquisition	7
Ending Balance	285	273
Unrealized gains or (losses) on liabilities held on Consolidated Balance Sheet	158	186
Other borrowed funds
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	2	7
Issuances	5	28
Settlements	(4)	(33)
Ending Balance	3	2
Other liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	43	137
Included in Earnings	151	17
Issuances	321	96
Settlements	(340)	(207)
Ending Balance	175	43
Unrealized gains or (losses) on liabilities held on Consolidated Balance Sheet	$ 111	$ 1

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This item represents the amount of the net change in unrealized (holding) gains or losses for the period which are included in the statement of income. Such unrealized (holding) gains or losses relate to those assets and liabilities still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3).

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Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Business Acquisition

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This element represents net gains or losses for the period (realized and unrealized), arising from assets and liabilities measure at fair value on a recurring basis using unobservable inputs (Level 3), which are included in earnings or resulted in a change in net asset value.

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Amount of unrealized gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3) and still held.

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Amount of unrealized gain (loss) recognized in income from liability measured at fair value on recurring basis using unobservable input (level 3) and still held.

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Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

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Amount of gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3).

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Amount of issuances of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of transfer of financial instrument classified as an asset into level 3 of the fair value hierarchy.

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Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of gain (loss) recognized in income from liability measured at fair value on recurring basis using unobservable input (level 3).

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Amount of issuances of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of purchases of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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