Income Taxes - Components of provision for income taxes (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2019
Provision for income tax benefit (expense)
Income tax expense	$ 5.6	$ 5.3
UK income tax (as a percent)		20.00%

Amount of current income tax expense (benefit) pertaining to taxable income (loss) from continuing operations.

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-Name Accounting Standards Codification
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-Publisher FASB
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-Publisher FASB
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration