Basis of Presentation - Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Balance as of December 31, 2013			$ 8,820
Foreign currency translation adjustments during period	422	86	515	(1,294)
Unrealized gain (loss) on investments during period	1,495	(3,546)	(3,057)	(8,404)
Current period other comprehensive income (loss)	1,917	(3,460)	(2,542)	(9,698)
Balance as of June 30, 2014	6,278		6,278
Foreign Currency Translation Adjustments
Balance as of December 31, 2013			1,215
Foreign currency translation adjustments during period			515
Balance as of June 30, 2014	1,730		1,730
Unrealized Gain (Loss) on Investments
Balance as of December 31, 2013			7,605
Unrealized gain (loss) on investments during period			(3,057)
Balance as of June 30, 2014	4,548		4,548
Accumulated Other Comprehensive Income
Balance as of December 31, 2013			8,820
Current period other comprehensive income (loss)			(2,542)
Balance as of June 30, 2014	$ 6,278		$ 6,278