Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred Tax Assets
Tax Net Operating Loss Carryforwards	$ 74,213	$ 48,722
Compensation Related	12,514	7,212
Other	2,553	2,564
Total Deferred Tax Assets	89,280	58,498
Valuation Allowance	(56,925)	(47,955)
Total Deferred Tax Asset, net of Valuation Allowance	32,355	10,543
Deferred Tax Liabilities
Intangible Assets	174,812	119,885
Property and Equipment	4,646	5,601
Other	1,061	1,926
Total Gross Deferred Tax Liability	180,519	127,412
Net Deferred Tax Liability	$ 148,164	$ 116,869