Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Estimated annual effective income tax rate			25.80%	31.60%
Percentage of allowable business interest expense deduction from adjusted taxable income			50.00%		30.00%
Effective income tax rate reconciliation, prior year income taxes, amount			$ 4.0
Effective income tax rate reconciliation, change in deferred tax assets valuation allowance, amount			$ 2.4
Income taxes as a percentage of pretax income	18.00%	13.70%	17.40%	18.70%
Net tax benefit included in income taxes, discrete items	$ 3.1	$ 3.0	$ 7.3	$ 6.7
Unrecognized tax benefits	1.9		1.9		$ 2.1
Unrecognized tax benefits with impact on the effective tax rate	1.9		1.9		2.0
Accrued interest expense and penalties	$ 0.8		$ 0.8		$ 0.8

Discrete income tax expense benefit.

No definition available.

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- Definition

Income tax expense percentage of pre tax income (loss).

+ References

No definition available.

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- Definition

Percentage of allowable business interest expense deduction from adjusted taxable income.

+ References

No definition available.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319

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- References

No definition available.

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319

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- Definition

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).

+ References

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- Definition

Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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