EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Basic EPS Calculation
Net income available for common stock	$ 93,660	$ 90,835
Weighted Average Number of Shares Outstanding, Basic	52,825	52,604
Earnings Per Share, Basic	$ 1.77	$ 1.73
Diluted EPS Calculation
Net income available for common stock	$ 93,660	$ 90,835
Effect of dilutive securities on income	$ 0	$ 0
Effect of dilutive securities on shares	381	293
Weighted Average Number of Shares Outstanding, Diluted	53,206	52,897
Earnings Per Share, Diluted	$ 1.76	$ 1.72