Income Taxes - Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Property, equipment and intangible assets	$ (17,212)	$ (8,026)
Accrued compensation	12,790	12,472
Accrued expenses	30,720	20,724
State Tax Credits	2,438	1,595
Foreign net operating losses	2,119	2,286
Valuation allowance on foreign net operating losses	(1,653)	(1,392)
Other	1,411	(474)
Net deferred tax assets	$ 30,613	$ 27,185