Mergers and Acquisitions - Narrative (Details) $ / shares in Units, $ in Thousands			3 Months Ended
	Feb. 18, 2022 USD ($)	Jan. 31, 2022 USD ($) $ / shares shares	Mar. 31, 2022 USD ($) $ / shares shares	Mar. 31, 2021 USD ($)	Jan. 30, 2022 shares	Jan. 01, 2022 USD ($)	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($)
Business Acquisition [Line Items]
Preferred stock, shares authorized (in shares) | shares		400,000,000	3,000,000		200,000,000		3,000,000
Depositary shares issued (in shares) | shares		5,400,000
Depositary share, interest in a share of preferred stock		0.025
Preferred stock, par value (in dollars per share) | $ / shares			$ 0.01				$ 0.01
Depositary share, liquidation preference (in dollars per share) | $ / shares		$ 25
Goodwill			$ 2,513,771	$ 538,373			$ 538,373	$ 538,373
Provision (benefit) for credit losses			188,845	$ (25,750)
Series A Preferred Stock
Business Acquisition [Line Items]
Preferred stock, dividend percentage		6.50%
Series G Preferred Stock
Business Acquisition [Line Items]
Preferred stock, dividend percentage		6.50%
Preferred stock, par value (in dollars per share) | $ / shares		$ 0.01
Liquidation preference (in dollars per share) | $ / shares		$ 1,000
Series F Preferred Stock
Business Acquisition [Line Items]
Preferred stock, dividend percentage		5.25%
Preferred stock, par value (in dollars per share) | $ / shares		$ 0.01
Liquidation preference (in dollars per share) | $ / shares		$ 25,000
Sterling
Business Acquisition [Line Items]
Share exchange ratio		0.4630
Goodwill		$ 1,939,432				$ 1,900,000
Provision (benefit) for credit losses			$ 175,100
Net assets acquired		$ 3,240,868
Sterling | Core deposits
Business Acquisition [Line Items]
Acquired intangible assets, useful life		10 years
Sterling | Customer relationships
Business Acquisition [Line Items]
Acquired intangible assets, useful life		10 years
Bend Financial, Inc.
Business Acquisition [Line Items]
Equity interests acquired	100.00%
Cash consideration	$ 55,300
Net assets acquired	19,300
Bend Financial, Inc. | Internal use software
Business Acquisition [Line Items]
Intangible assets acquired	15,900
Bend Financial, Inc. | Customer relationships
Business Acquisition [Line Items]
Intangible assets acquired	$ 3,000