Inventory Financing Agreements(Textual) (Detail) mbpd in Thousands					12 Months Ended
	Dec. 05, 2018 USD ($) mbpd	Jun. 27, 2018 USD ($)	Jun. 26, 2018 USD ($)	May 08, 2017	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jun. 01, 2018 USD ($)	Dec. 21, 2017	Dec. 01, 2016 USD ($) installment	Jun. 01, 2015 USD ($)
Supply and exchange agreement expenses					$ 39,768,000	$ 31,632,000	$ 28,506,000
Supply and Offtake Agreements
Commitment period				1 year
Debt instrument, interest rate				7.00%
Amount of deferred payment arrangement		$ 165,000,000	$ 125,000,000
Percentage of receivables and inventory for deferred payment		85.00%	85.00%
Purchase And Supply Commitment, Deferred Payment Arrangement, Aggregate Marginal Increase	$ 2,500,000
Barrels of crude per day provided by J. Aron | mbpd	150
Supply and exchange agreement expenses					4,500,000	2,300,000	3,200,000
Deferral arrangement fee											$ 1,300,000
Current borrowing capacity					77,400,000	83,100,000
Outstanding amount of deferred payment arrangement					68,400,000	41,100,000
Fee agreement receivable					$ 2,500,000	7,100,000		$ 2,200,000		$ 14,600,000
Number of fee agreement payments | installment										18
London Interbank Offered Rate (LIBOR) | Supply and Offtake Agreements
Basis spread on variable rate	3.50%
Deferred payment availability fee											0.75%
7.75% Senior Secured Note due 2025
Debt instrument, interest rate					7.75%
7.75% Senior Secured Note due 2025 | Senior Notes
Debt instrument, interest rate					7.75%				7.75%
Shipping and Handling [Member] | Supply and Offtake Agreements
Cost of goods and services sold					$ 21,500,000	$ 13,700,000	$ 7,800,000