Pension and Other Postretirement Benefit (Narrative) (Details) $ in Millions	9 Months Ended
Sep. 30, 2018 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plans, Number of Frozen Plans	2
Defined benefit plans, estimated benefit payments, in current fiscal year	$ 31.1
Estimated employer contributions in current year	$ 29.9

Amount of contributions expected to be received by defined benefit plan from employer in fiscal year. Excludes contributions paid by employer in current fiscal year.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2709-114920

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