Financial Instruments and Off-Balance Sheet Risk - Schedule of Gross Volume of Commodity Derivative Instruments Outstanding (Detail) bbl in Thousands, MMBTU in Thousands |
12 Months Ended | |
|---|---|---|
|
Dec. 31, 2016
MMBTU
bbl
|
Dec. 31, 2015
MMBTU
bbl
|
|
| Long contracts | Refined products contracts | ||
| Derivative Instruments and Hedging Activities Disclosures [Line Items] | ||
| Refined products, barrels | bbl | 9,882 | 12,067 |
| Long contracts | Natural gas contracts | ||
| Derivative Instruments and Hedging Activities Disclosures [Line Items] | ||
| Natural Gas (MMBTU's) | MMBTU | 131,240 | 123,711 |
| Short contracts | Refined products contracts | ||
| Derivative Instruments and Hedging Activities Disclosures [Line Items] | ||
| Refined products, barrels | bbl | 13,940 | 16,558 |
| Short contracts | Natural gas contracts | ||
| Derivative Instruments and Hedging Activities Disclosures [Line Items] | ||
| Natural Gas (MMBTU's) | MMBTU | 76,556 | 75,785 |