CALCULATION OF WEIGHTED AVERAGE SHARES OUTSTANDING FOR EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Earnings Per Share [Abstract]
Net income	$ 37,773	$ 25,077	$ 98,987	$ 74,324	$ 60,776
Basic weighted average shares outstanding	32,256,789	32,982,532	32,300,688	32,966,214
Plus unvested restricted stock	119,834	96,567	105,726	94,958
Diluted weighted shares outstanding	32,376,623	33,079,099	32,406,414	33,061,172
Earnings per common share
Basic	$ 1.17	$ 0.76	$ 3.06	$ 2.25
Diluted	$ 1.17	$ 0.76	$ 3.05	$ 2.25