Revenues - Disaggregation of Revenues by Geography (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Disaggregation Of Revenue [Line Items]
Disaggregation of revenue	$ 1,233.4	$ 1,173.6
United States [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenue	878.4	862.0
United Kingdom [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenue	150.3	156.2
Europe (excluding United Kingdom), Middle East and Africa [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenue	69.8	63.0
Asia-Pacific and Japan [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenue	69.0	45.4
Canada [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenue	48.0	28.6
Americas, excluding United States and Canada [Member]
Disaggregation Of Revenue [Line Items]
Disaggregation of revenue	$ 17.9	$ 18.4

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 924
-SubTopic 10
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856

+ Details