Borrowings - Narrative (Details) - USD ($)	Jul. 26, 2016	Aug. 05, 2014	Dec. 31, 2021	Dec. 31, 2020	Feb. 26, 2020
Line of Credit Facility [Line Items]
Long-term line of credit			$ 108,209,000	$ 107,683,000
Long-term borrowings			69,670,000	268,077,000
Proceeds from issuance of subordinated long-term debt	$ 147,400,000	$ 68,800,000
Subordinated Notes
Line of Credit Facility [Line Items]
Long-term borrowings			$ 69,670,000	$ 220,000,000
Interest rate, stated percentage	5.00%	5.75%	5.84%	5.42%
Face amount	$ 150,000,000	$ 70,000,000
Payments of debt issuance costs	$ 2,600,000	$ 1,200,000
Federal Home Loan Bank – current portion
Line of Credit Facility [Line Items]
Interest rate, stated percentage					1.81%
Long-term debt					$ 50,000,000
Maximum
Line of Credit Facility [Line Items]
Federal Home Loan Bank, advances, branch of FHLB bank, amount of advances			$ 1,100,000,000
C D A R S
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity			1,800,000,000
Long-term line of credit			79,000
I N D
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity			1,800,000,000
Long-term line of credit			1,600,000,000
Loan Agreement and Related Stock Security Agreement
Line of Credit Facility [Line Items]
Long-term line of credit			300,000,000
Federal Reserve Bank of Richmond
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity			549,000,000
Federal Funds
Line of Credit Facility [Line Items]
Debt instrument, unused borrowing capacity, amount			$ 155,000,000