Quarterly report pursuant to Section 13 or 15(d)

Financial Instruments, Fair Value, and Concentrations of Credit Risk - Summary of Fair Value Measurements and Financial Statement Presentation (Detail)

v3.19.1
Financial Instruments, Fair Value, and Concentrations of Credit Risk - Summary of Fair Value Measurements and Financial Statement Presentation (Detail)
$ in Thousands
Dec. 31, 2018
USD ($)
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]  
Fair Values of Assets $ 1
Fair Values of Liabilities 248
Forward Purchase Contracts [Member]  
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]  
Fair Values of Assets 1 [1]
Fair Values of Liabilities 248 [1]
Level 2 [Member]  
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]  
Fair Values of Assets 1
Fair Values of Liabilities 248
Level 2 [Member] | Forward Purchase Contracts [Member]  
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]  
Fair Values of Assets 1 [1]
Fair Values of Liabilities $ 248 [1]
[1] The fair value for forward purchase contracts is estimated based on commodity futures market prices.