Acquisition and Divestiture Activity (Narrative) (Details) $ / shares in Units, customer in Millions		1 Months Ended	12 Months Ended
	Jun. 01, 2021 USD ($)	May 31, 2020 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) segment	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Oct. 12, 2021 customer branch employee state	Dec. 31, 2018 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of customers converted | customer						2.6
Number of employees converted | employee						9,000
Number of branches converted | branch						600
Number of states converted | state						7
Goodwill			$ 10,916,000,000	$ 9,233,000,000	$ 9,233,000,000
Number of reportable segments | segment			3
Gain on disposition of business				5,740,000,000
Impairment charges related to goodwill			0	0	0
Total allowance			4,868,000,000	5,361,000,000	$ 2,742,000,000		$ 2,629,000,000
BBVA USA Bancshares, Inc.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment charges related to goodwill				$ 2,200,000,000
Non-PCD Loans
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total allowance			$ 1,000,000,000
Discontinued Operations, Disposed of by Sale | BlackRock, Inc.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on disposition of business		$ 4,300,000,000
Discontinued operations, number of shares contributed | shares		500,000
Core deposits
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Finite-lived intangible asset, useful life			10 years
Registered Secondary Offering | Discontinued Operations, Disposed of by Sale | BlackRock, Inc.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on disposition of business		$ 4,300,000,000
Sale of stock, number of shares issued in transaction (in shares) | shares		31,600,000
Sale of stock, price per share (in dollars per share) | $ / shares		$ 420
Sale of stock, consideration received on transaction		$ 14,200,000,000
Payments of stock issuance costs		$ 200,000,000
BlackRock, Inc. | Discontinued Operations, Disposed of by Sale | BlackRock, Inc.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of stock, number of shares issued in transaction (in shares) | shares		2,650,000
Sale of stock, price per share (in dollars per share) | $ / shares		$ 414.96
BBVA USA Bancshares, Inc.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Business combination, consideration transferred	$ 11,480,000,000
Acquisition costs			$ 798,000,000
Direct acquisition-related cost			52,000,000
Cumulative nonrecurring merger and integration costs			$ 805,000,000
Goodwill	1,599,000,000
ACL at acquisition	1,102,000,000
Total loans and leases	61,423,000,000
BBVA USA Bancshares, Inc. | Fair Value
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total loans and leases	61,423,000,000
BBVA USA Bancshares, Inc. | Carrying Amount
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total loans and leases	62,269,000,000
BBVA USA Bancshares, Inc. | Non-PCD Loans | Fair Value
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total loans and leases	52,100,000,000
BBVA USA Bancshares, Inc. | Non-PCD Loans | Carrying Amount
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total loans and leases	52,000,000,000
BBVA USA Bancshares, Inc. | Purchased impaired loans | Fair Value
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total loans and leases	9,400,000,000
BBVA USA Bancshares, Inc. | Purchased impaired loans | Carrying Amount
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total loans and leases	$ 10,300,000,000