Inventory Financing Agreements - Supply and Offtake Agreements (Details) $ in Thousands				3 Months Ended		9 Months Ended
	Jan. 11, 2019	Dec. 05, 2018 USD ($) mbpd	Jun. 27, 2018	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Feb. 01, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jun. 03, 2019 USD ($)	Mar. 01, 2019 USD ($)	Dec. 19, 2018 USD ($)	Jun. 01, 2018 USD ($)	Jun. 01, 2015 USD ($)
Supply Commitment [Line Items]
Supply and exchange agreement expenses				$ 17,523	$ 18,348	$ 52,611	$ 57,336
London Interbank Offered Rate (LIBOR)
Supply Commitment [Line Items]
Margin on LIBOR rate	3.25%
Supply and Offtake Agreements
Supply Commitment [Line Items]
Agreement extension term						1 year
Deferred payment arrangement, aggregate marginal increase										$ 2,500	$ 2,500	$ 2,500
Barrels of crude per day provided (up to) (in mbpd) | mbpd		150
Supply and exchange agreement expenses				400	1,300	$ 2,500	4,300
Amount of deferred payment arrangement		$ 165,000
Percentage of receivables and inventory for deferred payment arrangement			85.00%
Deferral arrangement fee														$ 1,300
Capacity of deferred payment arrangement				66,500		66,500			$ 155,500
Outstanding amount of deferred payment arrangement				51,900		51,900			97,500
Fee agreement receivable (payable)				800		800		$ 800	$ 500				$ 2,200
Supply and Offtake Agreements | London Interbank Offered Rate (LIBOR)
Supply Commitment [Line Items]
Margin on LIBOR rate		3.50%
Deferred payment availability fee		0.75%
Supply and Offtake Agreements | Inventory Intermediation
Supply Commitment [Line Items]
Handling fees				$ 2,200	$ 9,100	$ 8,900	$ 24,700