STOCKHOLDERS' EQUITY, Stock Options (Details) - Stock Options [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Stock Option Activity [Abstract]
Outstanding at beginning of period (in shares)			1,066	1,017
Granted (in shares)			220	338
Exercised (in shares)			(150)	(86)
Forfeited (in shares)			(39)	0
Cancelled (in shares)			(19)
Outstanding at end of period (in shares)	1,078	1,269	1,078	1,269
Exercisable at end of period (in shares)	603	742	603	742
Weighted Average Exercise Price [Abstract]
Outstanding at beginning of period (in dollars per share)			$ 45.32	$ 37.29
Granted (in dollars per share)			85.23	60.78
Exercised (in dollars per share)			32.54	34.93
Forfeited (in dollars per share)			70.57	0
Cancelled (in dollars per share)			58.61
Outstanding at end of period (in dollars per share)	$ 54.10	$ 43.71	54.10	43.71
Exercisable, end of period (in dollars per share)	$ 40.83	$ 33.03	$ 40.83	$ 33.03
Aggregate intrinsic value, outstanding, beginning of period			$ 41,161	$ 23,927
Aggregate intrinsic value, outstanding, end of period	$ 27,001	$ 20,626	27,001	20,626
Aggregate intrinsic value, exercisable, end of period	$ 22,249	$ 19,769	$ 22,249	$ 19,769
Weighted average remaining contractual term, outstanding			6 years 7 months 6 days	6 years 7 months 6 days
Weighted average remaining contractual term, exercisable			4 years 8 months 12 days	4 years 10 months 24 days
Weighted Average Assumptions [Abstract]
Dividend yield			0.50%	0.50%
Expected volatility			30.00%	34.00%
Risk-free interest rate			1.80%	1.20%
Expected term			4 years 7 months 6 days	5 years
Weighted-average fair value of options granted (in dollars per share)	$ 20.54	$ 17.8	$ 23.21	$ 18.45
Total intrinsic value of stock options exercised	$ 2,375	$ 1,242	$ 7,596	$ 2,257