Other Assets (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Other	$ 39	$ 32
Restatement Adjustment [Member]
Other		$ 2

Amount of other miscellaneous assets expected to be realized or consumed after one year or normal operating cycle, if longer.

No definition available.

Name:	us-gaap_OtherAssetsMiscellaneousNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant