Debt, Non-Bank Debt and Capitalized Interest (Details) (USD $)	3 Months Ended		6 Months Ended		1 Months Ended					1 Months Ended					0 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Notes Due In 2013 [Member]	Jan. 31, 2013 Senior Notes Due In 2013 [Member]	Jun. 30, 2012 Gulf Opportunity Zone Revenue Bonds Series 2010 [Member]	Apr. 30, 2012 Tax Exempt Revenue Refunding Bonds Series 1997A [Member]	Mar. 31, 2012 Tax Exempt Revenue Refunding Bonds Series 1997A [Member]	Apr. 30, 2012 Notes Due In 2012 [Member]	Mar. 31, 2012 Tax Exempt Waste Disposal Revenue Bonds Series 1997 [Member]	Mar. 31, 2012 Tax Exempt Waste Disposal Revenue Bonds Series 1998 [Member]	Mar. 31, 2012 Tax Exempt Waste Disposal Revenue Bonds Series 1999 [Member]	Mar. 31, 2012 Tax Exempt Waste Disposal Revenue Bonds Series 2001 [Member]	May 03, 2012 Industrial Revenue Bonds Tax Exempt Refunding Bonds [Member]
Non-Bank Debt (Textual)
Debt repayments			$ 480,000,000	$ 862,000,000	$ 300,000,000	$ 180,000,000		$ 4,000,000		$ 750,000,000					$ 108,000,000
Interest rate of notes in percentage					4.75%	6.70%	4.00%	5.45%	5.45%	6.875%	5.60%	5.60%	5.70%	6.65%
Proceeds from Advances for Construction							300,000,000
Debt Instrument, Maturity Date							Dec. 01, 2040
Debt Instrument, Mandatory Tender Date							Jun. 01, 2022
Redemption value in percentage															100.00%
Capitalized Interest (Textual)
Interest costs incurred, capitalized	$ 45,000,000	$ 53,000,000	$ 85,000,000	$ 105,000,000