Income Taxes Level 4 Net Operating Loss Carryover (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Domestic		$ 1,894
Deferred Tax Assets, Operating Loss Carryforwards, Foreign		9
Expiring Tax Year 2020 [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	$ 1
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2020
Latest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2036
Expiring within Tax Years 2023 to 2036 [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	$ 5,164
No expiration tax year [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards	51
Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	5,165
Deferred Tax Assets, Operating Loss Carryforwards	1,808
Operating Loss Carryforwards		5,412
Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	51
Deferred Tax Assets, Operating Loss Carryforwards	$ 10
Operating Loss Carryforwards		$ 48