Merger, Acquisition, and Divestiture Activity - Additional Information (Details) $ / shares in Units, $ in Thousands		3 Months Ended	12 Months Ended
	Nov. 18, 2022 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Oct. 26, 2023 USD ($) $ / shares	Sep. 30, 2023 USD ($)	Dec. 31, 2020 USD ($)
Business Acquisition [Line Items]
Allowance for credit losses		$ 303,671	$ 307,610	$ 303,671	$ 107,341			$ 131,388
Plan assets		16,600	0	16,600
Assets		46,763,372	49,089,836	46,763,372
Total loans		31,123,641	32,991,927	31,123,641
Deposits		35,000,830	37,235,180	35,000,830
Deposits, health savings accounts	$ 382,000
Gain on sale of health savings accounts	$ 90,700		0	90,673	0
Property optimization		26,800	1,559	26,818	$ 0
First Midwest
Business Acquisition [Line Items]
Transaction costs, expensed			28,700	120,900
Allowance for credit losses		$ 96,300		$ 96,300
First Midwest | Unfunded Loan Commitment
Business Acquisition [Line Items]
Allowance for credit losses			$ 11,000
CapStar Financial Holdings, Inc.
Business Acquisition [Line Items]
Shares exchange ratio						1.155
Value of issuance common stock shares						$ 344,400
Share price (in dollars per share) | $ / shares						$ 16.64
CapStar Financial Holdings, Inc. | CapStar Financial Holdings, Inc.
Business Acquisition [Line Items]
Assets							$ 3,300,000
Total loans							2,300,000
Deposits							$ 2,800,000