Balance Sheet Components, Components of Other Current Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2015		Dec. 31, 2014
Balance Sheet Components [Abstract]
Accrued variable compensation	$ 9,465		$ 15,060
Deferred revenues	5,180		5,945
Payroll related costs	1,898		1,614
Accrued subcontractor fees	690		871
Accrued medical claims expense	1,581		1,615
Acquired liabilities	1,651		2,603
Estimated fair value of contingent consideration liability	2,414	[1]	0
Other current liabilities	3,972		5,320
Total	$ 26,851		$ 33,028

[1] Represents the fair value estimate of additional earnings-based contingent consideration that may be realized by Zeon's selling shareholders 12 months after the Zeon acquisition.