Borrowings (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Jul. 26, 2016	Aug. 05, 2014
Short-term Debt [Line Items]
Total short-term borrowings	$ 326,726	$ 280,980
Average daily balance short-term borrowings	309,471	165,723
Maximum month-end balance short-term borrowings	332,987	474,852
Total long-term borrowings	268,077	217,687
Subordinated Notes
Short-term Debt [Line Items]
Total long-term borrowings	220,000	220,000
Average daily balance long-term borrowings	220,000	220,000
Maximum month-end balance long-term borrowings	$ 220,000	$ 220,000
Interest rate, stated percentage	5.42%	5.42%	5.00%	5.75%
Average interest rate	5.42%	5.42%
Month-end interest rate	5.42%	5.42%
Borrowings
Short-term Debt [Line Items]
Total long-term borrowings	$ 50,000	$ 0
Average daily balance long-term borrowings	50,000	0
Maximum month-end balance long-term borrowings	$ 50,000	$ 0
Interest rate, stated percentage	1.81%	0.00%
Average interest rate	1.81%	0.00%
Month-end interest rate	1.81%	0.00%
Customer repurchase agreements and federal funds purchased
Short-term Debt [Line Items]
Total short-term borrowings	$ 26,726	$ 30,980
Average daily balance short-term borrowings	29,345	30,024
Maximum month-end balance short-term borrowings	$ 32,987	$ 34,852
Interest rate, stated percentage	0.26%	1.18%
Average interest rate	1.00%	1.15%
Month-end interest rate	1.13%	0.89%
Federal Home Loan Bank – current portion
Short-term Debt [Line Items]
Total short-term borrowings	$ 300,000	$ 250,000
Average daily balance short-term borrowings	280,126	135,699
Maximum month-end balance short-term borrowings	$ 300,000	$ 440,000
Interest rate, stated percentage	0.67%	0.39%
Average interest rate	0.66%	1.67%
Month-end interest rate	0.67%	0.92%