Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	$ 1,093,628	$ 1,096,183	$ 1,356,405
Total changes in other comprehensive income (loss)	19,349	907	1,223
Balance	1,338,191	1,093,628	1,096,183
Foreign currency translation adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	(2,080)	(971)	(325)
Other comprehensive (loss) income before reclassifications	(5,782)	(1,109)	(646)
Amounts reclassified from accumulated other comprehensive loss	0	0	0
Total changes in other comprehensive income (loss)	(5,782)	(1,109)	(646)
Balance	(7,862)	(2,080)	(971)
Unrealized holding gains (losses) on marketable securities, net of tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	126	(123)	42
Other comprehensive (loss) income before reclassifications	17,395	249	(165)
Amounts reclassified from accumulated other comprehensive loss	0	0	0
Total changes in other comprehensive income (loss)	17,395	249	(165)
Balance	17,521	126	(123)
Unrealized (losses) gains on foreign currency forward contracts, net of tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	3,778	2,011	(23)
Other comprehensive (loss) income before reclassifications	17,383	6,493	3,591
Amounts reclassified from accumulated other comprehensive loss	(9,647)	(4,726)	(1,557)
Total changes in other comprehensive income (loss)	7,736	1,767	2,034
Balance	11,514	3,778	2,011
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	1,824	917	(306)
Other comprehensive (loss) income before reclassifications	28,996	5,633	2,780
Amounts reclassified from accumulated other comprehensive loss	(9,647)	(4,726)	(1,557)
Total changes in other comprehensive income (loss)	19,349	907	1,223
Balance	$ 21,173	$ 1,824	$ 917