EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
EARNINGS PER SHARE OF COMMON STOCK, BASIC AND DILUTED [Line Items]
Net income	$ 44,704	$ 16,276	$ 20,419	$ 90,835	$ 47,119	$ 18,797	$ 20,623	$ 76,456	$ 172,234	$ 162,995	$ 140,095
Weighted Average Number of Shares Outstanding, Basic									52,693,000	52,527,000	52,453,000
Earnings Per Share, Basic	$ 0.85	$ 0.31	$ 0.39	$ 1.73	$ 0.90	$ 0.36	$ 0.39	$ 1.45	$ 3.27	$ 3.10	$ 2.67
Dilutive Securities, Effect on Basic Earnings Per Share									$ 0	$ 0	$ 0
Weighted Average Number Diluted Shares Outstanding Adjustment									336,000	452,000	510,000
Net Income (Loss) Available to Common Stockholders, Diluted									$ 172,234	$ 162,995	$ 140,095
Weighted Average Number of Shares Outstanding, Diluted									53,029,000	52,979,000	52,963,000
Earnings Per Share, Diluted	$ 0.84	$ 0.31	$ 0.39	$ 1.72	$ 0.89	$ 0.36	$ 0.39	$ 1.44	$ 3.25	$ 3.08	$ 2.65
Common Stock, Shares, Issued	52,598,005				52,598,005				52,598,005	52,598,005