Accounts Receivable, Net and Revenue Concentrations - Accounts Receivable, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Accounts Receivable, Net, Current [Abstract]
Trade receivables, gross	$ 154,181	$ 142,299
Allowance for doubtful accounts	(1,077)	(1,064)	$ (945)	$ (904)
Allowance for sales returns	(539)	(562)
Net trade receivables	152,565	140,673
Other	7,490	10,905
Accounts receivable, net	$ 160,055	$ 151,578