Debt (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended						0 Months Ended	1 Months Ended		1 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	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, 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]	Feb. 28, 2011 Senior Notes Due In February 2011 [Member]	Feb. 28, 2011 Gulf Opportunity Zone Revenue Bonds Series 2010 [Member]
Non-Bank Debt (Textual)
Debt repayments	$ 0	$ 510					$ 108	$ 4		$ 750	$ 210	$ 300
Interest rate of notes in percentage			5.60%	5.60%	5.70%	6.65%		5.45%	5.45%	6.875%	6.75%
Redemption value in percentage							100.00%
Capitalized Interest (Textual)
Interest costs incurred, capitalized	$ 52	$ 27