Parent Company Only Financial Information - Condensed Statements of Financial Condition (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash and due from banks	$ 157,388	$ 49,787
Goodwill	17,636	16,127
Other assets	84,759	59,494
Total assets	7,976,394	7,017,776
Subordinated debentures	90,180	74,319
Other liabilities	141,047	85,082
Total liabilities	7,357,397	6,438,104
Common stock	341	315
Additional paid-in capital	261,533	226,691
Treasury stock, at average cost (3,311,769 shares and 3,373,389 shares at December 31, 2020 and 2019, respectively)	(69,400)	(71,487)
Retained earnings	442,789	433,960
Accumulated other comprehensive loss, net of taxes	(16,266)	(9,807)
Total stockholders' equity	618,997	579,672	$ 549,464	$ 532,608
Total liabilities and stockholders' equity	7,976,394	7,017,776
Holding Company
Cash and due from banks	28,033	14,401
Other securities	1,295	1,332
Investment in Bank	726,802	684,643
Goodwill	2,185	2,185
Other assets	839	1,897
Total assets	759,154	704,458
Subordinated debentures	90,180	74,319
Junior subordinated debentures, at fair value	43,136	44,384
Other liabilities	6,841	6,083
Total liabilities	140,157	124,786
Common stock	341	315
Additional paid-in capital	261,533	226,691
Treasury stock, at average cost (3,311,769 shares and 3,373,389 shares at December 31, 2020 and 2019, respectively)	(69,400)	(71,487)
Retained earnings	442,789	433,960
Accumulated other comprehensive loss, net of taxes	(16,266)	(9,807)
Total stockholders' equity	618,997	579,672
Total liabilities and stockholders' equity	$ 759,154	$ 704,458