Income Taxes Level 4 AMT credit and foreign tax credit carryover (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	$ 160	$ 178
Deferred Tax Assets, Capital Loss Carryforwards	325	491
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	639	652
No expiration tax year [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	$ 639
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, 2024
Expiring within Tax Years 2018 to 2024 [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	$ 160
Expiring Tax Year 2019 [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Capital Loss Carryforwards	318
Expiring Tax Year 2020 [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Capital Loss Carryforwards	7
Before Tax [Member]
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Deferred Tax Asset	160	178
Deferred Tax Assets, Capital Loss Carryforwards	$ 114	$ 172