Loans and Allowance for Credit Losses for Loans - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non covered loans net of unearned discount and deferred loan fees	$ 62,000,000		$ 78,500,000
Accrued interest	87,600,000		83,700,000
Sales of loans	$ 0	$ 0
Number of consecutive months for performing restructured loans to be put on accrual status	6 months
TDRs not reported as non-accrual loans	$ 56,500,000		71,300,000
Non-performing TDRs	104,700,000		117,200,000
Specific reserves for loan losses	7,800,000	3,400,000
Loan charge-offs related to loans modified as TDRs	0	$ 5,100,000
Amount from modified loans	23,000,000		27,900,000
Other real estate owned	1,000,000		2,300,000
Residential real estate properties
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other real estate owned	0		0
In formal foreclosure proceedings
Accounts, Notes, Loans and Financing Receivable [Line Items]
Residential mortgage and consumer loans secured by residential real estate properties	$ 2,800,000		$ 2,500,000