Financings (Issuance of Common Stock) (Details) (USD $) In Millions, except Share data			3 Months Ended
	Jun. 30, 2011	Dec. 31, 2010	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