Parent Company Financial Statements, Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets [Abstract]
Cash on deposit	$ 54,250	$ 58,680
Goodwill	65,490	65,490
Premises and equipment, net	42,001	44,046
Other assets	35,887	37,731
Total assets	5,139,141	4,366,003
Liabilities and shareholders' equity [Abstract]
Long-term debt	57,841	57,841
Other liabilities	33,694	29,332
Total liabilities	4,484,276	3,751,117
Shareholders' equity	654,865	614,886	$ 564,150	$ 530,699
Total liabilities and shareholders' equity	5,139,141	4,366,003
Parent Company [Member]
Assets [Abstract]
Cash on deposit	1,505	2,089
Investment in and advances to subsidiaries	707,943	667,206
Goodwill	4,973	4,973
Premises and equipment, net	96	153
Deferred tax asset	4,649	5,100
Other assets	45	44
Total assets	719,211	679,565
Liabilities and shareholders' equity [Abstract]
Long-term debt	61,341	61,341
Other liabilities	3,005	3,338
Total liabilities	64,346	64,679
Shareholders' equity	654,865	614,886
Total liabilities and shareholders' equity	$ 719,211	$ 679,565