Summary of Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Net Interest Income	$ 75,160	$ 73,681	$ 73,118	$ 72,707	$ 62,700	$ 59,724	$ 57,644	$ 53,930	$ 294,666	$ 233,998	$ 203,073
Provision for loan losses	2,181	5,328	2,118	2,067	2,171	3,181	5,674	1,671	11,694	12,697	14,501
NET INTEREST INCOME AFTER PROVISION FOR LOAN LOSSES	72,979	68,353	71,000	70,640	60,529	56,543	51,970	52,259	282,972	221,301	188,572
Noninterest income	24,455	28,542	31,026	29,578	24,381	24,980	30,661	30,663	113,601	110,685	82,224
Noninterest expense	69,912	68,427	71,020	70,309	65,954	61,996	63,482	59,614	279,668	251,046	215,800
Income taxes	8,360	8,260	10,036	9,900	4,365	4,945	3,989	7,599	36,556	20,898	13,096
NET INCOME	19,162	20,208	20,970	20,009	14,591	14,582	15,160	15,709	80,349	60,042	41,900
Preferred dividends	(19)	(53)	(52)	(168)	(204)	(205)	(204)	(204)	(292)	(817)	(817)
Interest expense on convertible preferred debt	3	17	31	0	0	0	0	0	51	0	0
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	$ 19,146	$ 20,172	$ 20,949	$ 19,841	$ 14,387	$ 14,377	$ 14,956	$ 15,505	$ 80,108	$ 59,225	$ 41,083
Earnings per share — basic (in dollars per share)	$ 0.75	$ 0.82	$ 0.85	$ 0.84	$ 0.68	$ 0.70	$ 0.73	$ 0.77	$ 3.26	$ 2.87	$ 2.23
Earnings per share — diluted (in dollars per share)	0.74	0.81	0.84	0.82	0.67	0.69	0.72	0.76	3.22	2.83	2.19
Cash dividends declared on common stock (in dollars per share)	0.20	0.10	0.10	0.10	0.15	0.10	0.10	0.10	$ 0.50	$ 0.45	$ 0.40
Book value per common share (in dollars per share)	$ 28.31	$ 28.48	$ 27.88	$ 27.15	$ 25.92	$ 24.68	$ 24.13	$ 23.59
Weighted average common shares outstanding (in shares)	25,498,423	24,601,016	24,524,273	23,657,234	21,232,232	20,619,945	20,598,899	20,214,582	24,573,000	20,672,000	18,462,000
Weighted average diluted common shares outstanding (in shares)	25,800,472	24,922,946	24,974,995	24,117,384	21,419,699	20,893,312	20,877,236	20,493,266	24,873,000	20,929,000	18,742,000