Commitments And Contingencies Environmental Matters (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Environmental Exit Cost [Line Items]
Accrual for Environmental Loss Contingencies	$ 4	$ 5
Accrued Environmental Loss Contingencies, Noncurrent	$ 4	4
Accrued Liabilities
Environmental Exit Cost [Line Items]
Accrued Environmental Loss Contingencies, Current		1
Other Long-Term Liabilities
Environmental Exit Cost [Line Items]
Accrued Environmental Loss Contingencies, Noncurrent		$ 4