Debt (Schedule of Carrying Values of Debt) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Capital lease obligations	$ 101,400	$ 130,900
Total long-term debt obligations	1,027,400	1,023,200
Less unamortized deferred financing costs	(10,700)	(12,900)
Total debt, net of deferred financing costs	1,016,700	1,010,300
Current portion of long-term debt	66,106	77,400
Long-term debt	$ 950,641	932,868
Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, maturity date	Oct. 29, 2018
Credit Facility [Member] | Revolving Loans [Member]
Debt Instrument [Line Items]
Long-term debt obligations	$ 260,700	208,500
Credit Facility [Member] | Term Loan [Member]
Debt Instrument [Line Items]
Line of credit facility, maturity date	Nov. 21, 2019
Long-term debt obligations	$ 240,600	250,000
Senior Notes [Member] | 4.875% Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date	Mar. 15, 2023
Long-term debt obligations	$ 400,000	400,000
Other Credit Facilities [Member]
Debt Instrument [Line Items]
Long-term debt obligations	$ 15,400	16,400
Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Capital lease obligations, expiration date, range, end	Oct. 01, 2021
Notes Payable [Member]
Debt Instrument [Line Items]
Notes payable, maturity date, range, end	Dec. 15, 2018
Long-term debt obligations	$ 9,300	$ 17,400