Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets
Stock compensation	$ 7,723	$ 11,954
Deferred compensation	12,949	13,079
Accrued expenses	11,343	35,499
Deferred rent	4,033	5,492
Net operating losses	2,650	5,756
Other	4,904	6,576
Total deferred tax assets	43,602	78,356
Deferred tax liabilities
Intangibles	(51,551)	(78,201)
Fixed assets	(15,750)	(18,847)
Other	(3,297)	(2,545)
Total deferred tax liabilities	(70,598)	(99,593)
Valuation allowance	(40)	(183)
Net deferred tax liabilities	$ (27,036)	$ (21,420)