Income Taxes Level 4 AMT Credit and Foreign Tax Credit Carryover (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	$ 232	$ 232
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	$ 109	$ 122
Tax Credit Carryforward, Valuation Allowance			$ 1
Latest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Expiration Date	Dec. 31, 2024
Earliest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Expiration Date	Dec. 31, 2020
Valuation Allowance, Tax Credit Carryforward [Member]
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Valuation Allowance	$ 0