Income Taxes - Reconciliation of Difference Between Provision for Income Taxes and Expected Tax Provision at Weighted Average Tax Rate (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income tax provision (benefit) at expected rate	$ 0.8	$ 14.9
Tax effect of:
Nontaxable investment income	(0.1)	(0.4)
Foreign exchange adjustments	(2.0)	0.5
Withholding taxes	0.0	0.0
Prior period adjustments	0.0	0.0
Change in valuation allowance	0.0	(0.6)
Other	(1.5)	(5.5)
Income tax (benefit) provision	$ (2.8)	$ 8.9

Income tax reconciliation foreign exchange adjustments.

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Income tax reconciliation withholding taxes.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in the valuation allowance for deferred tax assets.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to revisions of previously reported income tax expense (benefit).

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