Pension and Postretirement Benefit Plans - Share of Amortization Expected to be Recognized (Details) $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($)
Defined Benefit Plan [Abstract]
Prior service benefit	$ (5.5)
Net actuarial loss	6.0
Total	$ 0.5

Amount of prior service cost (credit) recognized in net periodic benefit cost (credit) of defined benefit plan.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=112275985&loc=d3e4179-114921

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (h)(5)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (a)(5)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e2709-114920

Name:	us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration