Loans and Allowance for Credit Losses for Loans - Additional Information (Details) - USD ($)		3 Months Ended			9 Months Ended
	Apr. 01, 2022	Sep. 30, 2022	Jun. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non covered loans net of unearned discount and deferred loan fees		$ 136,500,000			$ 136,500,000		$ 78,500,000
Payments to acquire loans held-for-investment					5,900,000,000
Non covered loans net of earned discount and deferred loan fees		98,600,000			98,600,000
Accrued interest		139,600,000			139,600,000		83,700,000
Sales of loans		0		$ 0	$ 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		69,700,000			$ 69,700,000		71,300,000
Non-performing TDRs		155,700,000			155,700,000		117,200,000
Specific reserves for loan losses		71,500,000		8,200,000	71,500,000	8,200,000
Loan charge-offs related to loans modified as TDRs		3,800,000		$ 206,000	5,400,000	$ 6,000,000
Other real estate owned		286,000			286,000		2,300,000
Allowance for purchase credit deteriorated (PCD) loans					122,700,000
Allowance for purchase credit deteriorated (PCD) loans	$ 70,319,000				70,319,000
Financing receivable, excluding accrued interest, not purchased with credit deterioration, credit loss, expense (reversal)			$ 41,000,000
Residential real estate properties
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other real estate owned		0			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		$ 1,900,000			$ 1,900,000		$ 2,500,000