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Income Taxes - Narrative (Details) $ / shares in Units, ₩ in Millions, kr in Millions, $ in Millions			1 Months Ended		3 Months Ended		4 Months Ended		9 Months Ended		12 Months Ended
	Apr. 28, 2021 USD ($)	Apr. 28, 2021 DKK (kr)	Jan. 31, 2021 USD ($)	Jan. 31, 2021 DKK (kr)	Sep. 30, 2021 USD ($) $ / shares	Sep. 30, 2020 USD ($)	Aug. 31, 2021 USD ($)	Aug. 31, 2021 KRW (₩)	Sep. 30, 2021 USD ($) $ / shares	Sep. 30, 2020 USD ($) $ / shares	Dec. 31, 2017 USD ($)	Dec. 31, 2017 KRW (₩)	Dec. 31, 2016 USD ($)	Dec. 31, 2016 KRW (₩)
Income Taxes [Line Items]
Provision for income taxes					$ 10.0	$ 25.4			$ 20.8	$ 49.0
Effective income tax rate					30.90%	23.50%			26.10%	30.20%
Adjustment for discrete tax expense (benefit), prior year foreign tax return					$ 1.1	$ 16.1			$ 1.2	$ 16.1
Effective income tax rate reconciliation, expense (benefit) from other adjustments, amount						2.7				7.1
Effective income tax rate reconciliation, expense (benefit) from change in tax rate of foreign jurisdiction									(4.5)
Effective income tax rate reconciliation, expense (benefit) from disposition of business amount									(1.6)
Decrease in foreign income tax					$ (0.6)	$ 0.0			$ (1.2)	$ (1.5)
Basic earnings per common share (in dollars per share) | $ / shares					$ 0.01				$ 0.02	$ 0.02
Diluted earnings per common share (in dollars per share) | $ / shares					$ 0.01				$ 0.02	$ 0.02
Pre-assessment notice, amount							$ 9.0	₩ 10,600.0
Tax Authority, South Korea (SRTO) | Foreign Tax Authority | Assessment
Income Taxes [Line Items]
Pre-assessment notice, amount											$ 9.5	₩ 11,300.0	$ 9.9	₩ 11,700.0
2013 Tax Year | Danish Tax Authority | Foreign Tax Authority
Income Taxes [Line Items]
Estimated tax			$ 0.6	kr 3.7
2014 Tax Year | Danish Tax Authority | Foreign Tax Authority
Income Taxes [Line Items]
Estimated tax			$ 0.8	kr 4.9
2015 Tax Year | Danish Tax Authority | Foreign Tax Authority
Income Taxes [Line Items]
Estimated tax	$ 15.0	kr 96.1

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