Contingencies (Impact of Legal Expenses Paid or Incurred to Date and Settlements Paid or Deemed Final) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Loss Contingencies [Line Items]
Beginning Balance	$ 64
Settlements paid
Legal expenses incurred and/or paid
Ending Balance	64
Deductible [Member]
Loss Contingencies [Line Items]
Beginning Balance	18
Settlements paid
Legal expenses incurred and/or paid
Ending Balance	18
Company's Responsibility at 10% [Member]
Loss Contingencies [Line Items]
Beginning Balance	4
Settlements paid
Legal expenses incurred and/or paid
Ending Balance	4
Reduction to Amount Owed to CVR Holders at 90% [Member]
Loss Contingencies [Line Items]
Beginning Balance	42
Settlements paid
Legal expenses incurred and/or paid
Ending Balance	$ 42