Acquisition Activity (Narrative) (Details) employee in Thousands, customer in Millions, $ in Millions		3 Months Ended	6 Months Ended	18 Months Ended
	Jun. 01, 2021 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2022 USD ($) segment	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)	Oct. 12, 2021 customer branch employee state
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
Number of branches converted | branch						600
Number of states converted | state						7
Goodwill		$ 10,916	$ 10,916	$ 10,916	$ 10,916
Segment reporting, number of segments | segment			3
BBVA USA Bancshares, Inc.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Business combination, consideration transferred	$ 11,500
Acquisition costs		$ 14	$ 45
Cumulative nonrecurring merger and integration costs				$ 850
Goodwill	$ 1,599