Debt, Non-Bank Debt and Capitalized Interest (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		1 Months Ended						0 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Jan. 31, 2013 Senior Notes Due In 2013 [Member]	Mar. 31, 2012 Tax Exempt Revenue Refunding Bonds Series 1997A [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	$ 180	$ 0	$ 180						$ 108
Interest rate of notes in percentage			6.70%	5.45%	5.60%	5.60%	5.70%	6.65%
Redemption value in percentage									100.00%
Capitalized Interest (Textual)
Interest costs incurred, capitalized	$ 40	$ 52