INCOME TAXES (Effective Income Tax Reconciliation) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Statutory federal tax									$ 29,564	$ 26,102	$ 22,393
Increase/ (decrease) in taxes resulting from:
State taxes, net of federal benefit									311	368	280
Provision adjustment for current year uncertain tax position									(1,220)	0	0
Effect of permanent differences									8,589	2,524	2,177
Stock-based compensation									3,782	1,948	1,165
Rate differential between U.S. and foreign									(24,772)	(17,279)	(14,472)
Change in foreign tax rate									754	(59)	148
Change in valuation allowance									149	489	(489)
Other									155	683	177
Total	$ 6,159	$ 3,338	$ 3,587	$ 4,228	$ 4,553	$ 3,919	$ 3,317	$ 2,987	$ 17,312	$ 14,776	$ 11,379