Debt and Financing Obligations - Deferred Financing Fees, Supplemental Cash Flow (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
	Apr. 19, 2019	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Obligations
Deferred financing fees capitalized										$ 13,500
Unamortized fees		$ 18,000				$ 10,500				18,000	$ 10,500
Amortization expenses										5,038	5,372	$ 5,644
Supplemental Cash Flow Information [Abstract]
Net loss (gain) on sale and disposition of assets		(2,400)	$ 300	$ (1,100)	$ 500	100	$ 900	$ 3,000	$ 1,900	(2,730)	5,880	(1,624)
Sale Leaseback Sites [Member]
Financing Obligations
Unamortized fees		700				800				700	800
Supplemental Cash Flow Information [Abstract]
Net loss (gain) on sale and disposition of assets										0
Credit Agreement
Financing Obligations
Deferred financing fees capitalized										6,100
Unamortized fees		7,800				5,500				7,800	5,500
Reduction in applicable rate (as a percent)	0.25%
Write-off of a portion of the original issue discount and deferred financing fees	$ 200											600
Working Capital Facility [Member]
Supplemental Cash Flow Information [Abstract]
Borrowing from credit facility										1,758,700	2,002,700	1,311,700
Payments on credit facility										(1,688,100)	(1,976,100)	(1,509,600)
Net borrowings from (payments on) credit facility										70,600	26,600	(197,900)
Revolving Credit Facility [Member]
Financing Obligations
Reduction in applicable rate (as a percent)	0.25%
Supplemental Cash Flow Information [Abstract]
Borrowing from credit facility											166,000	36,300
Payments on credit facility										(27,300)	(142,000)	(57,000)
Net borrowings from (payments on) credit facility										(27,300)	24,000	$ (20,700)
All Senior Notes [Member]
Financing Obligations
Deferred financing fees capitalized										7,400
Unamortized fees		$ 9,500				$ 4,200				$ 9,500	$ 4,200