Commitments and Contingencies (Impact of Legal Expenses Paid or Incurred to Date and Settlements Paid or Deemed Final) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Loss Contingencies [Line Items]
Beginning Balance	$ 62	$ 58
Settlements paid		1
Legal expenses incurred and/or paid	2	3
Ending Balance	64	62
Deductible [Member]
Loss Contingencies [Line Items]
Beginning Balance	18	18
Ending Balance	18	18
Company's Responsibility at 10% [Member]
Loss Contingencies [Line Items]
Beginning Balance	4	4
Ending Balance	4	4
Reduction to Amount Owed to CVR Holders at 90% [Member]
Loss Contingencies [Line Items]
Beginning Balance	40	36
Settlements paid		1
Legal expenses incurred and/or paid	2	3
Ending Balance	$ 42	$ 40