Income Taxes (Operating Loss Carryforwards Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Operating Loss Carryforwards [Line Items]
Net operating loss and credit carryforwards	$ 5,500
Operating Loss Carryforwards, Valuation Allowance	$ 4
Minimum [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Jan. 01, 2017
Maximum [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Jan. 01, 2036