CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 5,135	$ 129,535	[1]	$ 85,436
Other comprehensive income (loss):
Unrealized gain on available-for-sale securities				1,488
Reclassification of unrealized gain to a realized gain on available-for-sale securities				(24,465)
Foreign currency translation adjustments	16,744	(22,524)		(28,716)
Total other comprehensive income (loss)	16,744	(22,524)		(51,693)
Comprehensive income	$ 21,879	$ 107,011		$ 33,743

[1] The Company adopted ASU 2016-09, Compensation - Stock Compensation: Improvements to Employee Share-Based Payment Accounting, ("ASU 2016-09") during the year ended December 31, 2016. The Company elected to early adopt ASU 2016-09 in the third quarter of 2016, which requires it to reflect any adjustments as of January 1, 2016, the beginning of the annual period that includes the interim period of adoption. The impact of the adoption to the Company's previously reported quarterly results for the quarters ended March 31 and June 30, 2016 are reflected in the table above.