| **Income Taxes - Textual (Details) - USD ($) $ in Millions**                       | 3 Months Ended | 9 Months Ended | 12 Months Ended |
|------------------------------------------------------------------------------------|----------------|----------------|-----------------|
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| **Income Tax Contingency [Line Items]**                                            |           |           |            |   |   |
| Provision for income tax expense                                                   | $ 42.1         | $ 35.9         | $ 124.2         | $ 98.4 |   |
| Net deferred tax assets                                                            | 72.6           |           | 72.6            |   |   |
| Valuation allowance                                                                | 28.3           |           | 28.3            |   |   |
| Operating loss carryforward from excess tax benefits of share-based awards         | 15.6           |           | 15.6            |   |   |
| Tax benefit resulting from automatic tax accounting method change                  | 7.0            |           | 7.0             |   |   |
| Additional tax benefits expected if accounting method change is accepted           |           |           | 0.1             |   |   |
| Gross unrecognized tax benefits                                                    | 2.8            |           | 2.8             |   | $ 2.9 |
| Gross unrecognized tax benefits that would impact effective tax rate if recognized | 2.8            |           | 2.8             |   | 2.9 |
| Anticipated release of unrecognized tax benefits within next 12 months             | 2.6            |           | 2.6             |   |   |
| Estimate [Member]                                                                  |           |           |            |   |   |
| **Income Tax Contingency [Line Items]**                                            |           |           |            |   |   |
| Tax benefit of combined federal NOL and tax credits                                | $ 18.0         |           | 18.0            |   |   |
| Additional tax benefits expected if accounting method change is accepted           |           |           | $ 50.0          |   | $ 44.0 |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of decrease reasonably possible in the next twelve months for the unrecognized tax benefit.
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| - Definition
Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.
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| - Definition
Amount, before allocation of a valuation allowances, of deferred tax assets attributable to deductible tax credit carryforwards including, but not limited to, research, foreign, general business, alternative minimum tax, and other deductible tax credit carryforwards.
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| - Definition
Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from share-based compensation.
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| - Definition
Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from the allowance for doubtful accounts.
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| - Definition
Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
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| - Definition
Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.
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| - Definition
Amount of unrecognized tax benefits.
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| - Definition
Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.
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| - Definition
The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.
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