Debt and Credit Arrangements - Interest Expense And Financing Cost Amortization (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Line of Credit Facility
Interest expense, debt	$ 17.7	$ 15.9	$ 9.3
Financing costs amortization	3.0	1.3	1.3
Revolving Credit Facility
Line of Credit Facility
Interest expense, debt	15.9	11.8	2.7
Financing costs amortization	2.0	0.6	0.6
Revolving Credit Facility \| Interest expense, term loan due June 2024
Line of Credit Facility
Interest expense, debt	8.4
Revolving Credit Facility \| Senior secured revolving credit facility
Line of Credit Facility
Interest expense, debt	$ 7.5	$ 11.8	$ 2.7

Amount of amortization expense attributable to debt issuance costs.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(8))
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399

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