Debt (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		1 Months Ended					1 Months Ended					0 Months Ended	1 Months Ended				1 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Gulf Opportunity Zone Revenue Bonds Series 2010 [Member]	Feb. 28, 2011 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, 2011 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]	Apr. 30, 2011 Industrial Revenue Bonds Tax Exempt Refunding Bonds [Member]	May 31, 2011 Senior Notes Due In May 2011 [Member]	Apr. 30, 2011 Tax Exempt Revenue Refunding Bonds Series 1997B [Member]	Apr. 30, 2011 Tax Exempt Revenue Refunding Bonds Series 1997C [Member]	Feb. 28, 2011 Senior Notes Due In February 2011 [Member]
Non-Bank Debt (Textual)
Proceeds from financing arrangement					$ 300
Debt repayments			862	718		300	4			750					108	8	200			210
Interest rate of notes in percentage					4.00%		5.45%	5.45%	5.45%	6.875%	5.60%	5.60%	5.70%	6.65%			6.125%	5.40%	5.40%	6.75%
Debt instrument maturity date (month, day, year)					Dec. 01, 2040
Debt instrument mandatory tender date					Jun. 01, 2022
Redemption value in percentage															100.00%
Capitalized Interest (Textual)
Interest costs incurred, capitalized	$ 53	$ 33	$ 105	$ 60