Long-term Debt and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Jan. 31, 2017	Jul. 15, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Total long-term debt		$ 1,044,108	$ 1,043,255
Less: Current portion of long-term debt (included in Other current liabilities)		(418)	(306)
Long-term debt, excluding current portion		1,043,690	1,042,949
Letters of Credit Outstanding, Amount		100,700
Line of Credit Facility, Remaining Borrowing Capacity		591,100
Line of Credit Facility, Commitment Fee Percentage	0.15%
Guarantor Obligations, Maximum Exposure		25,000
Guarantor Obligation, Collateral Amount		67,300
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,000,000
line of credit facility increase increment limit	$ 250,000
Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.10%
Revolving Credit Facility [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.10%
Revolving Credit Facility [Member] | letters of credit sublimit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 200,000
Fair Value, Inputs, Level 2 [Member]
Debt Instrument [Line Items]
Fair value of long-term debt		$ 1,125,000	$ 1,118,000