Fair Value Measurements - Schedule of estimated fair values of financial instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Financial assets
Debt securities held to maturity	$ 808,885
Portfolio loans, net	7,579,392	$ 7,101,111
Financial liabilities
Short-term borrowings	16,225	17,678
Junior subordinated debt owed to unconsolidated trusts	71,765	71,635
Level 1 Inputs | Carrying Amount
Financial assets
Cash and cash equivalents	347,149	836,095
Level 1 Inputs | Fair Value
Financial assets
Cash and cash equivalents	347,149	836,095
Level 2 Inputs | Carrying Amount
Financial assets
Debt securities held to maturity	936,328	0
Loans held for sale	4,546	0
Accrued interest receivable	37,409	31,064
Financial liabilities
Time deposits	800,187	935,649
Securities sold under agreements to repurchase	234,597	270,139
Short-term borrowings	16,225	17,678
Long-term debt	33,000	46,056
Junior subordinated debt owed to unconsolidated trusts	71,765	71,635
Accrued interest payable	5,075	2,728
Level 2 Inputs | Fair Value
Financial assets
Debt securities held to maturity	808,885	0
Loans held for sale	4,555	0
Accrued interest receivable	37,409	31,064
Financial liabilities
Time deposits	775,441	935,778
Securities sold under agreements to repurchase	234,597	270,139
Short-term borrowings	16,255	17,673
Long-term debt	33,071	46,164
Junior subordinated debt owed to unconsolidated trusts	60,603	63,586
Accrued interest payable	5,075	2,728
Level 3 Inputs | Carrying Amount
Financial assets
Portfolio loans, net	7,579,392	7,101,111
Mortgage servicing rights	6,564	8,608
Other servicing rights	1,862	1,830
Level 3 Inputs | Fair Value
Financial assets
Portfolio loans, net	7,319,530	7,161,466
Mortgage servicing rights	18,815	12,133
Other servicing rights	2,253	2,268
Level 3 Inputs | Senior Notes | Carrying Amount
Financial liabilities
Long-term debt	0	39,944
Level 3 Inputs | Senior Notes | Fair Value
Financial liabilities
Long-term debt	0	40,400
Level 3 Inputs | Subordinated Debt | Carrying Amount
Financial liabilities
Long-term debt	221,835	182,773
Level 3 Inputs | Subordinated Debt | Fair Value
Financial liabilities
Long-term debt	$ 209,000	$ 195,600