|
Risk Management Activities and Fair Value Measurements Risk Management Activities and Fair Value Measurements - Additional Information (Details) (USD $)
In Millions, unless otherwise specified |
Sep. 30, 2013
|
Jun. 30, 2013
|
|---|---|---|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Available-for-sale Securities, Amortized Cost Basis | $ 1,604 | $ 1,604 |
| Long Term Debt, Current Maturities measured at Fair Value | $ 2,064 | $ 4,540 |