Variable Interest Entities (Details) (USD $)			12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 T.E.S. Filer City [Member]	Dec. 31, 2011 Grayling [Member]	Dec. 31, 2011 Genesee [Member]	Dec. 31, 2011 Guarantee to Creditors [Member]	Dec. 31, 2011 Deferred Receivables [Member]	Dec. 31, 2011 Trust Preferred Securities [Member]
Variable Interest Entity, Effect of Consolidation, Change in Equity Method Investment		$ 5,000,000
Variable Interest Entity, Effect of Consolidation, Change in Long-term Debt		34,000,000
Variable Interest Entity, Effect of Consolidation, Change in Liabilities		29,000,000
Debt Instrument, Face Amount	7,093,000,000	7,206,000,000						29,000,000
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	52,000,000	49,000,000
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage			50.00%	50.00%	50.00%
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount						$ 3,000,000	$ 6,000,000