Income Taxes - Summary of Valuation Allowance Activity (Details) - Deferred Tax Asset Valuation Allowance - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 99.3	$ 91.5	$ 6.9
Net Change	4.7	7.8	84.6
Balance at End of Year	$ 104.0	$ 99.3	$ 91.5

Amount of valuation and qualifying accounts and reserves.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09(Column B))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24092-122690

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09(Column E))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24092-122690

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant