Income Taxes - Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Valuation Allowance [Line Items]
Property, equipment and intangible assets	$ (9,171)	$ (8,899)
Accrued compensation	17,365	16,274
Accrued expenses	43,176	35,415
Foreign operations	(941)	(868)
Foreign net operating losses	2,064	1,897
Deferred tax asset on unrecognized tax positions	1,107	1,200
Other	335	(1,555)
Net deferred tax assets	52,520	41,928
Foreign Operations
Valuation Allowance [Line Items]
Valuation allowance, foreign	(145)	(153)
Foreign Net Operating Losses
Valuation Allowance [Line Items]
Valuation allowance, foreign	$ (1,270)	$ (1,383)