Inventory Financing Agreements (Details) barrel / d in Thousands			3 Months Ended		9 Months Ended
	May 08, 2017 USD ($)	Jun. 01, 2015 USD ($) barrel / d	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Jul. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Feb. 29, 2016 USD ($) installment	Sep. 30, 2015 USD ($) payment
Supply Commitment [Line Items]
Supply and exchange agreement expenses			$ 7,419,000	$ 11,232,000	$ 25,500,000	$ 21,951,000
Supply and Offtake Agreements
Supply Commitment [Line Items]
Agreement extension term	1 year
Forward sale liability	$ 30,000,000
Barrels of crude per day provided (up to) | barrel / d		94
Handling fees			3,400,000	1,700,000	9,800,000	5,600,000
Supply and exchange agreement expenses			800,000	$ 900,000	2,300,000	$ 2,200,000
Amount of deferred payment arrangement		$ 125,000,000
Percentage of receivables and inventory for deferred payment arrangement		85.00%
Deferral arrangement fee		$ 1,300,000
Variable interest rate basis		P3M
Capacity of deferred payment arrangement			75,500,000		75,500,000			$ 59,400,000
Outstanding amount of deferred payment arrangement			41,800,000		41,800,000			43,300,000
Fee agreement receivable			$ (10,300,000)		$ (10,300,000)		$ (3,000,000)	$ (14,600,000)	$ (14,600,000)	$ (18,000,000)
Number of fee agreement payments									18	14
Supply and Offtake Agreements | London Interbank Offered Rate (LIBOR)
Supply Commitment [Line Items]
Margin on LIBOR rate		3.75%
Deferred payment availability fee		0.75%