Income Taxes - Temporary Differences (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Insurance reserves	$ 74.0	$ 125.0
Investments	79.0	75.0
Compensation and benefits	51.0	55.0
Other assets	0.0	3.0
Total gross assets	204.0	258.0
Net unrealized investment (gains) losses	(45.0)	(311.0)
Deferred policy acquisition costs	(205.0)	(134.0)
Deferred Tax Liabilities, Other	18.0	0.0
Total gross liabilities	(268.0)	(445.0)
Net deferred income tax asset (liability)	$ (64.0)	$ (187.0)

Amount of deferred tax liability attributable to taxable temporary differences.

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The tax effect as of the balance sheet date of the amount of the estimated future tax deductions arising from estimated policyholder reserves, which will be deductible from future taxable income when actual costs are incurred, and which can only be realized if sufficient tax-basis income is generated in future periods to enable the tax deduction to be taken.

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