Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss) at beginning of period	$ (12,892)	$ (11,014)	$ (22,617)	$ (20,836)
Other comprehensive income (loss) before reclassifications	99	374	9,913	11,562
Amounts reclassified from other comprehensive income	(503)	(133)	(592)	(1,499)
Net other comprehensive income (loss) during the period	(404)	241	9,321	10,063
Accumulated other comprehensive income (loss) at end of period	(13,296)	(10,773)	(13,296)	(10,773)
Unrealized Gains (Losses) on Available-For-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss) at beginning of period	0	(4)	(4)	(2)
Other comprehensive income (loss) before reclassifications	(4)	4	0	2
Amounts reclassified from other comprehensive income	0	0	0	0
Net other comprehensive income (loss) during the period	(4)	4	0	2
Accumulated other comprehensive income (loss) at end of period	(4)	0	(4)	0
Unrealized Holding Gains (Losses) on Derivative Transactions [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss) at beginning of period	5,246	(2,417)	6,773	6,087
Other comprehensive income (loss) before reclassifications	(5,537)	(787)	(6,975)	(7,925)
Amounts reclassified from other comprehensive income	(503)	(133)	(592)	(1,499)
Net other comprehensive income (loss) during the period	(6,040)	(920)	(7,567)	(9,424)
Accumulated other comprehensive income (loss) at end of period	(794)	(3,337)	(794)	(3,337)
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss) at beginning of period	(18,138)	(8,593)	(29,386)	(26,921)
Other comprehensive income (loss) before reclassifications	5,640	1,157	16,888	19,485
Amounts reclassified from other comprehensive income	0	0	0	0
Net other comprehensive income (loss) during the period	5,640	1,157	16,888	19,485
Accumulated other comprehensive income (loss) at end of period	$ (12,498)	$ (7,436)	$ (12,498)	$ (7,436)