Basis of Presentation Basis of Presentation (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Jan. 01, 2019
Accounting Standards Update 2016-02 [Member] \| Forecast [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Operating lease, right-of-use asset		$ 3.0
Other Pension, Postretirement and Supplemental Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pension and Other Postretirement Benefits Cost (Reversal of Cost)	$ 0.1

Amount of lessee's right to use underlying asset under operating lease.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977

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