Share-based Compensation - Allocated Share-based Compensation (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based compensation	$ 12.3	$ 8.4	$ 12.3
Income tax benefit	(2.3)	(1.5)	(2.2)
Total share-based compensation expense, net of tax	10.0	6.9	10.1
Stock option expense
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based compensation	1.7	0.6	3.0
ESPP expense
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based compensation	0.6	0.5	0.7
RSU, DSU and PSU expense
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based compensation	$ 10.0	$ 7.3	$ 8.6

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

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