Income Taxes - Deferred Tax and Liabilities Arising from Temporary Differences (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Receivables	$ 19,327	$ 19,705
Accrued liabilities	106,506	96,537
Net operating loss carryforwards	117,511	108,429
Other	36,712	37,794
Deferred tax assets	280,056	262,465
Valuation allowance	(70,474)	(61,282)
Net deferred tax assets	209,582	201,183
Intangible assets	(555,822)	(501,763)
Property and equipment	(118,008)	(100,376)
Investments in partnerships	(67,354)	(61,529)
Other	(30,934)	(23,762)
Deferred tax liabilities	(772,118)	(687,430)
Net deferred tax liabilities	$ (562,536)	$ (486,247)