CONSOLIDATED STATEMENTS OF SHAREHOLDERS EQUITY (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Stockholders' Equity [Abstract]
Tax effect of unrealized gain on derivative instruments	$ (22)	$ 22	$ 0
Tax effect of unrealized gain on available-for-sale investments	248	(279)	40
Tax benefit of foreign currency translation adjustment	$ (228)	$ (711)	$ (870)