CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Comprehensive Income (Loss), Foreign Currency Translation Gain (Loss) Arising During Period, Tax	$ (13,670)	$ (2,314)	$ 7,151
Net gains (losses) on cash flow hedging instruments, deferred income taxes	(544)	(975)	(338)
Pension liability adjustments, deferred income taxes	34	1,443	17,554
Unrealized gain (loss) on marketable securities, deferred income taxes	$ (16)	$ 10	$ (3)