Subsequent Events (Details) - Long-term Debt, Type [Domain] - Share Repurchase Program [Domain] - Investment [Domain] - Debt Instrument, Name [Domain] - Extinguishment of Debt, Type [Domain] - Scenario, Unspecified [Domain] $ / shares in Units, shares in Millions, $ in Millions				1 Months Ended	3 Months Ended			6 Months Ended		60 Months Ended	61 Months Ended
	Jul. 29, 2015 USD ($) MW	Jul. 17, 2015 $ / shares	Jul. 01, 2015 USD ($)	Aug. 07, 2015 USD ($) shares	Jun. 30, 2015 USD ($) $ / shares shares	Mar. 31, 2015 USD ($)	Jun. 30, 2014 USD ($) $ / shares	Jun. 30, 2015 USD ($) $ / shares	Jun. 30, 2014 USD ($) $ / shares	Jun. 30, 2015 USD ($) $ / shares shares	Aug. 07, 2015 USD ($) $ / shares shares
Subsequent Event [Line Items]
Common Stock, Dividends, Per Share, Declared | $ / shares					$ 0.10		$ 0.05	$ 0.10	$ 0.05
Treasury Stock, Shares, Acquired | shares					20.8					129.5
Treasury Stock Acquired, Average Cost Per Share | $ / shares										$ 12.47
Stock Repurchase Program, Remaining Authorized Repurchase Amount					$ 117			$ 117		$ 117
Gains (Losses) on Extinguishment of Debt					$ (122)	$ 23	$ (15)	$ (145)	$ (149)
Armenia Mountain [Member]
Subsequent Event [Line Items]
Proceeds from Divestiture of Businesses			$ 70
Subsequent Event [Member]
Subsequent Event [Line Items]
Common Stock, Dividends, Per Share, Declared | $ / shares		$ 0.10
Treasury Stock, Shares, Acquired | shares				2.2							131.7
Treasury Stock Acquired, Average Cost Per Share | $ / shares											$ 12.48
Stock Repurchase Program, Remaining Authorized Repurchase Amount				$ 88							$ 88
Subsequent Event [Member] | Solar Spain [Member]
Subsequent Event [Line Items]
Sale of Stock, Percentage of Ownership before Transaction	50.00%
Equity Method Investment, Net Sales Proceeds	$ 32
Generation Capacity Mega Watts | MW	31