Contingencies (UST Litigations Narrative) (Details) - UST Litigation [Member]	3 Months Ended
Mar. 31, 2018 plantiff	Jul. 31, 2016 case
WEST VIRGINIA [Member]
Loss Contingencies [Line Items]
Number of plaintiffs \| plantiff	6
CALIFORNIA [Member]
Loss Contingencies [Line Items]
Number of cases pending \| case		1

Number of pending claims pertaining to a loss contingency.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14435-108349

Name:	us-gaap_LossContingencyPendingClaimsNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant