Leases (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Tax Deficiency Paid In December 2005 [Member]	Dec. 31, 2011 Interest In April 2006 [Member]	Dec. 31, 2011 Disallowance Of Tax 1998-2007 [Member]	Dec. 31, 2010 Disallowance Of Tax 2010 [Member]	Dec. 31, 2009 Disallowance Of Tax 2009 [Member]	Dec. 31, 2008 Disallowance Of Tax 2008 [Member]
Operating Leased Assets [Line Items]
Accumulated amortization	$ 66	$ 59
Lease in lease out total investment	259
Lease in lease out total financed by equity	93
Lease in lease out total financed by long-term debt	166
The company's investment in leverage leases	(55)	(41)
Gross investment in leverage leases	234	235
Deferred tax liabilities	289	276
Tax deficiency paid to IRS			0.3
Interest paid related to tax deficiency				0.2
Disallowed deduction					416	40	41	42
Tax savings from lease in lease out transactions	236
Interest paid	$ 111