Employee Benefit Plans Plan Assets (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Pension plan assets, fair value	$ 115	[1]	$ 116	[1]	$ 122
Percentage of investment in mutual funds allocated to fixed income securities under the postretirement plan	74.00%		74.00%
Percentage of investment in mutual funds allocated to U.S. equity securities under the postretirement plan	18.00%		18.00%
Percentage of investment in mutual funds allocated to international equity securities under the postretirement plan	8.00%		8.00%
Estimated future contribution to postretirement benefit plan in next fiscal year	7
Savings Plan [Abstract]
Maximum Percentage Of Employee Compensation Eligible For Contribution To Savings Plan (in hundredths)	50.00%
Percentage of employer match under the savings plan (in hundredths)	100% of the first 6% of each employee’s compensation contributed
Savings Plan Benefit Expense	12		12		12
Postemployment Benefits [Abstract]
Postemployment benefit income (expense)	(3)		(3)		0
Postemployment benefit obligations	16		16
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Benefit expense related to deferred compensation plans	1		1		1
Other non-qualified plans benefit obligations deferred compensation	15		15
Fair Value, Inputs, Level 1 [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Pension plan assets, fair value	115	[1]	116	[1]
Fair Value, Inputs, Level 2 [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Pension plan assets, fair value	0	[1]	0	[1]
Fair Value, Inputs, Level 3 [Member]
Schedule Of Fair Value Of Financial Assets For Pension And Postretirement Benefits [Line Items]
Pension plan assets, fair value	0	[1]	0	[1]
Other Postretirement Benefit Plans, Defined Benefit [Member]
Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
Postretirement benefit payments - 2013	21
Postretirement benefit payments - 2014	22
Postretirement benefit payments - 2015	23
Postretirement benefit payments - 2016	24
Postretirement benefit payments - 2017	25
Postretirement benefit payments - 2018-2022	136
Medicare Subsidy Receipts - 2013	(2)
Medicare Subsidy Receipts - 2014	(2)
Medicare Subsidy Receipts - 2015	(2)
Medicare Subsidy Receipts - 2016	(3)
Medicare Subsidy Receipts - 2017	(3)
Medicare Subsidy Receipts - 2018-2022	$ (16)

[1] 74% of the amount invested in mutual funds is in fixed income securities; 18% is in U.S. equities and 8% is in international equities.