Parent Corporation Only Financial Statements (Details) - Condensed Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income	$ 20,783	$ 21,696	$ 19,281	$ 11,635	$ 18,672	$ 19,902	$ 17,527	$ 4,251	$ 73,395	$ 60,352	$ 43,220
Adjustments to reconcile net income to net cash provided by operating activities:
Loss on equity securities, net									(294)	267
Amortization of subordinated debt issuance costs									329	332	165
(Increase) decrease in other assets									(22,619)	(1,134)	5,706
(Decrease) increase in other liabilities									(2,785)	4,988	3,887
Net cash provided by operating activities									60,688	89,060	131,133
Cash flows from investing activities:
Sales of available-for-sale securities									183,728		29,543
Sales of equity securities									569
Net cash provided by (used) in investing activities									(102,467)	(357,214)	(817,727)
Cash flows from financing activities:
Cash dividends on common stock									(12,160)	(9,664)	(9,612)
Secondary offering and issuance of common stock											(180)
Repurchase of stock									(12,643)
Proceeds from exercise of stock options									360	875	417
Net cash provided by financing activities									70,896	290,938	635,777
(Decrease) increase in cash and cash equivalents									29,117	22,784	(50,817)
Cash and cash equivalents at beginning of period				172,366				149,582	172,366	149,582	200,399
Cash and cash equivalents at end of period	201,483				172,366				201,483	172,366	149,582
Parent Company [Member]
Cash flows from operating activities:
Net income									73,395	60,352	43,220
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed earnings of subsidiary									(49,079)	(49,235)	(33,458)
Loss on equity securities, net									38	4
Amortization of subordinated debt issuance costs									329	332	165
(Increase) decrease in other assets										(959)	104
(Decrease) increase in other liabilities									(1,509)	3,843	(151)
Net cash provided by operating activities									23,174	14,337	9,880
Cash flows from investing activities:
Purchase of available-for-sale securities									(2)	(8)	(7)
Sales of available-for-sale securities									23
Sales of equity securities									569
Capital infusion to subsidiary										(64,500)
Net cash provided by (used) in investing activities									590	(64,508)	(7)
Cash flows from financing activities:
Proceeds from subordinated debt										73,525
Cash dividends on common stock									(12,160)	(9,664)	(9,612)
Secondary offering and issuance of common stock											(180)
Repurchase of stock									(12,643)
Proceeds from exercise of stock options									360	875	417
Net cash provided by financing activities									(24,443)	64,736	(9,375)
(Decrease) increase in cash and cash equivalents									(679)	14,565	498
Cash and cash equivalents at beginning of period				$ 22,071				$ 7,506	22,071	7,506	7,008
Cash and cash equivalents at end of period	$ 21,392				$ 22,071				$ 21,392	$ 22,071	$ 7,506