Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2018	Sep. 30, 2018	Dec. 31, 2017
Effective tax rate (as a percent)	24.50%	22.60%
Statutory Federal income tax rate (as a percent)	21.00%	21.00%
Capital loss carryforward valuation allowance		$ 0.9
Revaluation of net deferred tax liabilities for the Tax Act			$ 246.8
Alternative minimum tax credits	$ 13.9	13.9
Accounting Standards Update 2016-09
Discrete tax benefit		$ 4.6

Represents the amount of tax benefit from capital loss carryforward valuation allowance.

No definition available.

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Amount of reasonable estimate for income tax expense (benefit) for remeasurement of deferred tax from change in tax rate pursuant to Tax Cuts and Jobs Act of 2017 for which accounting for tax effect is incomplete.

+ References

No definition available.

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- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible alternative minimum tax credit carryforwards.

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- Definition

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

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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- Definition

Amount of tax benefit from exercise of stock options granted under share-based compensation arrangement.

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