Segments and Related Information (Reconciliation of EBITDA to Consolidated Income from Continuing Operations before Income Taxes) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Less:
Interest expense, net	$ (12,643,000)	$ (12,666,000)	$ (37,595,000)	$ (34,549,000)
Depreciation and amortization	(41,747,000)	(37,756,000)	(111,996,000)	(103,111,000)
Income from continuing operations before income taxes	73,772,000	81,633,000	151,655,000	170,608,000
Continuing Operations [Member]
Segments and Related Information [Line Items]
EBITDA	$ 128,200,000	$ 132,100,000	$ 301,200,000	$ 308,300,000