Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Consolidated Statements Of Comprehensive Income [Abstract]
Net income (loss)	$ (31,965)	$ 64,047	$ 95,401
Other comprehensive income (loss):
Foreign currency translation adjustments	4,977	(1,465)	(3,391)
Unrealized gain (loss) on investments, net of tax	33	21	(31)
Unrealized gain on derivative, net of tax	1,192	286	0
Other, net of tax	(175)	(2)	(119)
Net current period other comprehensive gain (loss)	6,027	(1,160)	(3,541)
Comprehensive income (loss)	$ (25,938)	$ 62,887	$ 91,860