Income Taxes Level 4 AMT credit and foreign tax credit carryover (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	180	$ 178
Deferred Tax Assets, Capital Loss Carryforwards	494	491
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	652	652
No expiration tax year [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	0
Earliest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Expiration Date	Dec. 31, 2018
Latest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Expiration Date	Dec. 31, 2025
Expiring within Tax Years 2018 to 2024 [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	180
Expiring Tax Year 2019 [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Capital Loss Carryforwards	491
Expiring Tax Year 2020 [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Capital Loss Carryforwards	3
Before Tax [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Capital Loss Carryforwards	173	172
Tax Credit Carryforward, Deferred Tax Asset	180	$ 178

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible capital loss carryforwards.

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