STOCKHOLDERS' EQUITY, Stock Options (Details) - Stock Options [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Stock Option Activity [Abstract]
Outstanding at beginning of period (in shares)	1,066	1,017
Granted (in shares)	216	333
Exercised (in shares)	(108)	(39)
Forfeited (in shares)	(7)	0
Cancelled (in shares)	(6)
Outstanding at end of period (in shares)	1,161	1,311
Exercisable at end of period (in shares)	644	781
Weighted Average Exercise Price [Abstract]
Outstanding at beginning of period (in dollars per share)	$ 45.32	$ 37.29
Granted (in dollars per share)	85.38	60.71
Exercised (in dollars per share)	36.57	34.11
Forfeited (in dollars per share)	57.20	0
Cancelled (in dollars per share)	58.42
Outstanding at end of period (in dollars per share)	53.46	43.36
Exercisable, end of period (in dollars per share)	$ 39.62	$ 32.98
Aggregate intrinsic value, outstanding, beginning of period	$ 41,161	$ 23,927
Aggregate intrinsic value, outstanding, end of period	34,272	24,481
Aggregate intrinsic value, exercisable, end of period	$ 27,584	$ 22,692
Weighted average remaining contractual term, outstanding	6 years 10 months 24 days	6 years 8 months 12 days
Weighted average remaining contractual term, exercisable	5 years 1 month 6 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)	$ 23.27	$ 18.46
Total intrinsic value of stock options exercised	$ 5,221	$ 1,015