QUARTERLY FINANCIAL DATA (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
Interest income															$ 137,716	$ 106,240	$ 74,910
Interest expense															16,845	10,129	7,460
Net interest income															120,871	96,111	67,450
Provision for loan losses															5,550	4,000	2,200
Net interest income after provision for loan losses															115,321	92,111	65,250
Non-interest income															16,046	12,668	8,166
Non-interest expenses															77,081	72,890	52,414
Income before income taxes															54,286	31,889	21,002
Income tax expense															18,795	10,778	7,239
Net Income															$ 35,491	$ 21,111	$ 13,763
Basic earnings per share (in dollars per share)															$ 2.01	$ 1.43	$ 1.18
Diluted earnings per share (in dollars per share)															$ 2.00	$ 1.43	$ 1.18
Parent Company
Interest income	$ 34,615		$ 34,761	$ 34,733	$ 33,607		$ 31,609		$ 31,744		$ 22,380		$ 20,507
Interest expense	4,450		4,077	4,143	4,175		3,705		2,659		1,953		1,812		$ 5,903	$ 2,626	$ 1,365
Net interest income	30,165		30,684	30,590	29,432		27,904		29,085		20,427		18,695
Provision for loan losses	1,400		2,000	900	1,250		1,000		1,500		700		800
Net interest income after provision for loan losses	28,765		28,684	29,690	28,182		26,904		27,585		19,727		17,895
Non-interest income	3,748		4,034	4,269	3,995		3,411		3,926		2,527		2,804
Non-interest expenses	18,529	[1]	19,204	20,441	18,907	[2]	18,173	[3]	19,373	[4]	22,034	[5]	13,310	[6]	260	73	86
Income before income taxes	13,984		13,514	13,518	13,270		12,142		12,138		220		7,389
Income tax expense	4,824		4,663	4,664	4,644		4,147		4,248		(243)		2,626		(2,126)	(933)	(463)
Net Income	$ 9,160		$ 8,851	$ 8,854	$ 8,626		$ 7,995		$ 7,890		$ 463		$ 4,763		$ 35,491	$ 21,111	$ 13,763
Basic earnings per share (in dollars per share)	$ 0.5		$ 0.5	$ 0.51	$ 0.49		$ 0.46		$ 0.45		$ 0.04		$ 0.41
Diluted earnings per share (in dollars per share)	$ 0.5		$ 0.5	$ 0.5	$ 0.49		$ 0.46		$ 0.45		$ 0.04		$ 0.41

[1] 2016 amount includes reversal of costs associated with the CNB and FNBNY acquisitions of $0.7 million.

[2] 2016 amount includes reversal of costs associated with the CNB and FNBNY acquisitions of $0.3 million.

[3] 2015 amount includes costs associated with the CNB acquisition of $0.5 million.

[4] 2015 amount includes costs associated with the CNB acquisition of $0.9 million.

[5] 2015 amount includes costs associated with the CNB acquisition of $8.2 million.

[6] 2015 amount includes costs associated with the CNB acquisition of $0.2 million.