Financings (Issuance of Common Stock) (Details) (USD $) In Millions, except Share data | 3 Months Ended | |||
|---|---|---|---|---|
Sep. 30, 2011 | Dec. 31, 2010 | Sep. 30, 2011
Continuous Equity Program [Member] | Jun. 30, 2011
Continuous Equity Program [Member] | |
| Aggregate sales price of an equity offering program | $ 50 | |||
| Shares of common stock issued | 762,925 | |||
| Per share value of common stock issued | $ 19.66 | |||
| Value of common stock issued | 15 | |||
| Issuance of Common Stock Net Proceeds | $ 3 | $ 2 | ||