Investments In and Advances To Affiliates (Details) (Entek [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2011	Mar. 31, 2011	Sep. 30, 2011 mw
Entek [Member]
Investments In And Advances To Affiliates General Disclosure [Abstract]
Effective Ownership %			49.60%
Generation Capacity (MW)			312
Cash paid for acquisition	$ 13	$ 136	$ 149