Commitments And Contingencies Environmental Matters (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Environmental Exit Cost [Line Items]
Accrual for Environmental Loss Contingencies	$ 4	$ 4
Accrued Environmental Loss Contingencies, Noncurrent	3	3
Accrued Liabilities
Environmental Exit Cost [Line Items]
Accrued Environmental Loss Contingencies, Current	1	1
Other Long-Term Liabilities
Environmental Exit Cost [Line Items]
Accrued Environmental Loss Contingencies, Noncurrent	$ 3	$ 3