Income Taxes Level 4 AMT credit and foreign tax credit carryover (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	$ 138	$ 154
Deferred Tax Assets, Capital Loss Carryforwards	21	78
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	639	639
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, 2020
Latest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Expiration Date	Dec. 31, 2024
Expiring within Tax Years 2019 to 2024 [Member] [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	$ 138
Expiring Tax Year 2019 [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Capital Loss Carryforwards	60
Before Tax [Member]
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Deferred Tax Asset	$ 138	$ 154