Income Taxes (Schedule of Deferred Tax Asset (Liability)) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Components of Deferred Tax Assets and Liabilities [Abstract]
NOLs and tax credit carry forwards	$ 69,771	$ 82,636
Compensation and benefit plans	30,880	49,710
Allowance for doubtful accounts	370	421
Fixed assets and intangible assets	24,737	46,595
Interest rate swap contracts	1,893	2,884
Accrued interest expense	13,049	11,567
Other liabilities	12,562	20,811
Deferred tax asset	153,262	214,624
Valuation allowance	(57,121)	(71,563)
Net deferred tax asset, noncurrent	96,141	143,061
Prepaid liabilities	(501)	(819)
Fixed assets and intangible assets	(61,127)	(78,616)
Investments in partnerships	(103,474)	(177,376)
Other assets	(20,657)	(23,444)
Deferred tax liability, noncurrent	185,759	280,255
Total net deferred tax liability	$ (89,618)	$ (137,194)