Financial Instruments and Off-Balance Sheet Risk - Summary of Realized and Unrealized (Losses) and Gains on Derivative Instruments for Commodity Risk Management (Detail) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Derivative Instruments and Hedging Activities Disclosures [Line Items] | |||
| Realized and unrealized (losses) and gains on derivative instruments | $ (18,163) | $ 169,565 | $ 190,123 |
| Refined products contracts | |||
| Derivative Instruments and Hedging Activities Disclosures [Line Items] | |||
| Realized and unrealized (losses) and gains on derivative instruments | (25,316) | 149,741 | 159,751 |
| Natural gas contracts | |||
| Derivative Instruments and Hedging Activities Disclosures [Line Items] | |||
| Realized and unrealized (losses) and gains on derivative instruments | $ 7,153 | $ 19,824 | $ 30,372 |