|
Risk Management Activities and Fair Value Measurements - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified |
Dec. 31, 2011
|
Jun. 30, 2011
|
|---|---|---|
| Disclosure Risk Management Activities and Fair Value Measurements Additional Information [Abstract] | ||
| Derivative, Net Liability Position, Aggregate Fair Value | $ 377 | |
| Long-Term Debt Fair Value Disclosure | $ 21,950 | $ 23,418 |