EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Basic EPS Calculation
Net income available for common stock	$ 17,457	$ 24,470	$ 93,660	$ 16,276	$ 20,419	$ 90,835	$ 135,587	$ 127,530
Weighted Average Number of Shares Outstanding, Basic	52,933			52,736			52,883	52,678
Earnings Per Share, Basic	$ 0.33			$ 0.31			$ 2.56	$ 2.42
Diluted EPS Calculation
Net income available for common stock	$ 17,457	$ 24,470	$ 93,660	$ 16,276	$ 20,419	$ 90,835	$ 135,587	$ 127,530
Effect of dilutive securities on income	$ 0			$ 0			$ 0	$ 0
Effect of dilutive securities on shares	334			376			346	291
Weighted Average Number of Shares Outstanding, Diluted	53,267			53,112			53,229	52,969
Earnings Per Share, Diluted	$ 0.33			$ 0.31			$ 2.55	$ 2.41