Quarterly Results of Operations (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]
Interest income	$ 65,005	$ 64,376	$ 62,704	$ 61,227	$ 56,514	$ 56,538	$ 55,202	$ 52,944	$ 253,312	$ 221,198	$ 208,879
Interest expense	6,631	6,694	6,742	6,772	6,440	6,215	6,171	5,968	26,839	24,794	21,842
NET INTEREST INCOME	58,374	57,682	55,962	54,455	50,074	50,323	49,031	46,976	226,473	196,404	187,037
Provision for loan losses	2,417	1,900	790	550			417		5,657	417	2,560
NET INTEREST INCOME AFTER PROVISION FOR LOAN LOSSES	55,957	55,782	55,172	53,905	50,074	50,323	48,614	46,976	220,816	195,987	184,477
Non-interest income	16,120	16,861	16,385	15,837	14,031	16,332	24,106	15,399	65,203	69,868	61,816
Non-interest expense	41,934	44,115	44,835	46,475	45,510	43,031	45,896	40,369	177,359	174,806	164,008
INCOME BEFORE INCOME TAX	30,143	28,528	26,722	23,267	18,595	23,624	26,824	22,006
Income tax expense	7,850	7,469	6,716	5,574	4,418	6,557	8,856	5,834	27,609	25,665	22,123
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	$ 22,293	$ 21,059	$ 20,006	$ 17,693	$ 14,177	$ 17,067	$ 17,968	$ 16,172	$ 81,051	$ 65,384	$ 60,162
Basic EPS (in dollars per share)	$ 0.55	$ 0.51	$ 0.50	$ 0.43	$ 0.37	$ 0.46	$ 0.47	$ 0.43	$ 1.99	$ 1.73	$ 1.66
Diluted EPS (in dollars per share)	$ 0.55	$ 0.51	$ 0.49	$ 0.43	$ 0.37	$ 0.45	$ 0.47	$ 0.43	$ 1.98	$ 1.72	$ 1.65
Average Shares Outstanding:
Basic (in shares)	40,846,650	40,779,423	40,751,720	40,690,573	37,908,873	37,850,827	37,793,448	37,709,883	40,767,343	37,816,399	36,266,356
Diluted (in shares)	41,124,179	41,025,784	40,969,111	40,916,972	38,190,694	38,118,199	38,043,359	38,000,074	41,013,133	38,088,233	36,554,609