INCOME TAXES (Effective Income Tax Reconciliation) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Statutory federal tax									$ 44,263	$ 37,125	$ 29,564
Increase/ (decrease) in taxes resulting from:
State taxes, net of federal benefit									1,192	341	311
Provision adjustment for current year uncertain tax position									0	0	(1,220)
Effect of permanent differences									5,042	7,314	8,589
Stock-based compensation expense									9,535	7,591	3,782
Foreign tax expense and tax rate differential									(33,477)	(31,094)	(24,772)
Change in foreign tax rate									0	9	754
Change in valuation allowance									0	0	149
Other									645	328	155
Total	$ 7,287	$ 7,067	$ 6,493	$ 6,353	$ 7,095	$ 5,800	$ 5,209	$ 3,510	$ 27,200	$ 21,614	$ 17,312