Income Taxes Income Tax Loss and Tax Credit Carryforwards, State and Local, Net of Federal Tax Effect, By Expiration Dates (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011
2012 through 2016 [Member]
Income Tax Loss and Tax Credit Carryforwards, State and Local, Net of Federal Tax Effect [Line Items]
United States state and local income tax loss carryforwards - net of federal tax effect	$ 6
United States state and local income tax credit carryforwards - net of federal tax effect	11
2017 through 2021 [Member]
Income Tax Loss and Tax Credit Carryforwards, State and Local, Net of Federal Tax Effect [Line Items]
United States state and local income tax loss carryforwards - net of federal tax effect	4
United States state and local income tax credit carryforwards - net of federal tax effect	9
2022 through 2026 [Member]
Income Tax Loss and Tax Credit Carryforwards, State and Local, Net of Federal Tax Effect [Line Items]
United States state and local income tax loss carryforwards - net of federal tax effect	11
United States state and local income tax credit carryforwards - net of federal tax effect	5
2027 through 2031 [Member]
Income Tax Loss and Tax Credit Carryforwards, State and Local, Net of Federal Tax Effect [Line Items]
United States state and local income tax loss carryforwards - net of federal tax effect	8
United States state and local income tax credit carryforwards - net of federal tax effect	5
Not subject to expiration [Member]
Income Tax Loss and Tax Credit Carryforwards, State and Local, Net of Federal Tax Effect [Line Items]
United States state and local income tax loss carryforwards - net of federal tax effect	0
United States state and local income tax credit carryforwards - net of federal tax effect	6
Valuation allowance [Member]
Income Tax Loss and Tax Credit Carryforwards, State and Local, Net of Federal Tax Effect [Line Items]
United States state and local income tax loss carryforwards - net of federal tax effect	(8)
United States state and local income tax credit carryforwards - net of federal tax effect	$ (15)