Fair Value Measurements - Estimated fair value of company's financial instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Assets
Federal funds sold	$ 20,391	$ 28,200
Interest bearing deposits with other banks	1,680,945	1,752,420
Investment securities available-for-sale, at fair value	2,623,408	1,150,885
Liabilities
Interest bearing deposits	777,255	756,923
Customer repurchase agreements	23,918	26,726
Carrying Value
Assets
Cash and due from banks	12,886	8,435
Federal funds sold	20,391	28,200
Interest bearing deposits with other banks	1,680,945	1,752,420
Investment securities available-for-sale, at fair value	2,623,408	1,150,885
Federal Reserve and Federal Home Loan Bank stock	34,153	40,104
Loans held for sale	47,218	88,205
Loans	7,065,598	7,650,633
Liabilities
Noninterest bearing deposits	3,277,956	2,809,334
Interest bearing deposits	5,974,502	756,923
Time deposits	729,082	977,760
Customer repurchase agreements	23,918	26,726
Borrowings	369,670	568,077
Carrying Value | Mortgage banking derivatives
Assets
Derivative asset	636	5,213
Carrying Value | Interest Rate Caps
Assets
Derivative asset	5,197
Liabilities
Derivative liability	5,147	3,574
Carrying Value | Interest Rate Swap
Assets
Derivative asset		3,413
Liabilities
Derivative liability	0	516
Carrying Value | Credit Risk Contract
Liabilities
Derivative liability	47	118
Fair Value
Assets
Cash and due from banks	12,886	8,435
Federal funds sold	20,391	28,200
Interest bearing deposits with other banks	1,680,945	1,752,420
Investment securities available-for-sale, at fair value	2,623,408	1,150,885
Federal Reserve and Federal Home Loan Bank stock	34,153	40,104
Loans held for sale	47,218	88,205
Loans	6,930,929	7,608,687
Liabilities
Noninterest bearing deposits	3,277,956	2,809,334
Interest bearing deposits	5,974,502	756,923
Time deposits	736,001	993,500
Customer repurchase agreements	23,918	26,726
Borrowings	374,326	575,435
Fair Value | Mortgage banking derivatives
Assets
Derivative asset	636	5,213
Fair Value | Interest Rate Caps
Assets
Derivative asset	5,197
Liabilities
Derivative liability	5,147	3,574
Fair Value | Interest Rate Swap
Assets
Derivative asset		3,413
Liabilities
Derivative liability	0	516
Fair Value | Credit Risk Contract
Liabilities
Derivative liability	47	118
Fair Value | Fair Value, Inputs, Level 1
Assets
Cash and due from banks	12,886	8,435
Federal funds sold	0	0
Interest bearing deposits with other banks	0	0
Investment securities available-for-sale, at fair value	0	0
Federal Reserve and Federal Home Loan Bank stock	0	0
Loans held for sale	0	0
Loans	0	0
Liabilities
Noninterest bearing deposits	0	0
Interest bearing deposits	0	0
Time deposits	0	0
Customer repurchase agreements	0	0
Borrowings	0	0
Fair Value | Fair Value, Inputs, Level 1 | Mortgage banking derivatives
Assets
Derivative asset	0	0
Fair Value | Fair Value, Inputs, Level 1 | Interest Rate Caps
Assets
Derivative asset	0
Liabilities
Derivative liability	0	0
Fair Value | Fair Value, Inputs, Level 1 | Interest Rate Swap
Assets
Derivative asset		0
Liabilities
Derivative liability	0	0
Fair Value | Fair Value, Inputs, Level 1 | Credit Risk Contract
Liabilities
Derivative liability	0	0
Fair Value | Fair Value, Inputs, Level 2
Assets
Cash and due from banks	0	0
Federal funds sold	20,391	28,200
Interest bearing deposits with other banks	1,680,945	1,752,420
Investment securities available-for-sale, at fair value	2,611,408	1,149,385
Federal Reserve and Federal Home Loan Bank stock	34,153	40,104
Loans held for sale	47,218	88,205
Loans	0	0
Liabilities
Noninterest bearing deposits	3,277,956	2,809,334
Interest bearing deposits	5,974,502	756,923
Time deposits	736,001	993,500
Customer repurchase agreements	23,918	26,726
Borrowings	374,326	575,435
Fair Value | Fair Value, Inputs, Level 2 | Mortgage banking derivatives
Assets
Derivative asset	0	0
Fair Value | Fair Value, Inputs, Level 2 | Interest Rate Caps
Assets
Derivative asset	5,197
Liabilities
Derivative liability	5,147	3,574
Fair Value | Fair Value, Inputs, Level 2 | Interest Rate Swap
Assets
Derivative asset		3,413
Liabilities
Derivative liability	0	516
Fair Value | Fair Value, Inputs, Level 2 | Credit Risk Contract
Liabilities
Derivative liability	47	118
Fair Value | Fair Value, Inputs, Level 3
Assets
Cash and due from banks	0	0
Federal funds sold	0	0
Interest bearing deposits with other banks	0	0
Investment securities available-for-sale, at fair value	12,000	1,500
Federal Reserve and Federal Home Loan Bank stock	0	0
Loans held for sale	0	0
Loans	6,930,929	7,608,687
Liabilities
Noninterest bearing deposits	0	0
Interest bearing deposits	0	0
Time deposits	0	0
Customer repurchase agreements	0	0
Borrowings	0	0
Fair Value | Fair Value, Inputs, Level 3 | Mortgage banking derivatives
Assets
Derivative asset	636	5,213
Fair Value | Fair Value, Inputs, Level 3 | Interest Rate Caps
Assets
Derivative asset	0
Liabilities
Derivative liability	0	0
Fair Value | Fair Value, Inputs, Level 3 | Interest Rate Swap
Assets
Derivative asset		0
Liabilities
Derivative liability	0	0
Fair Value | Fair Value, Inputs, Level 3 | Credit Risk Contract
Liabilities
Derivative liability	$ 0	$ 0