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, 2015
MMBTU
bbl
|
Dec. 31, 2014
MMBTU
bbl
|
|
| Refined Products [Member] | Long Contracts [Member] | ||
| Derivative Instruments and Hedging Activities Disclosures [Line Items] | ||
| Refined products, barrels | bbl | 12,067 | 10,823 |
| Refined Products [Member] | Short Contracts [Member] | ||
| Derivative Instruments and Hedging Activities Disclosures [Line Items] | ||
| Refined products, barrels | bbl | 16,558 | 15,434 |
| Natural Gas [Member] | Long Contracts [Member] | ||
| Derivative Instruments and Hedging Activities Disclosures [Line Items] | ||
| Natural gas, MMBTUs | MMBTU | 123,711 | 131,376 |
| Natural Gas [Member] | Short Contracts [Member] | ||
| Derivative Instruments and Hedging Activities Disclosures [Line Items] | ||
| Natural gas, MMBTUs | MMBTU | 75,785 | 82,796 |