Stock-Based Compensation Plans - Additional Information (Detail) $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($) Stock_Plan shares	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option compensation	$ 6.6	$ 4.9	$ 4.1
Accrued liabilities	$ 154.0	132.1
Stock Options Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration term for stock granted	10 years
Aggregate number of shares of common stock reserved for issuance which can be granted \| shares	2,550,000
Number of stock option plans \| Stock_Plan	2
Number exercisable and fully vested \| shares	41,525
Fully vested stock options with performance conditions attached \| shares	8,530
Stock option compensation	$ 6.6	4.9	4.2
Total intrinsic value exercised	3.5	3.2	2.9
Total compensation cost related to non-vested stock options not yet recognized	$ 8.6
Expected compensation cost recognized over the weighted-average period	1 year 9 months 3 days
Current tax benefit related to stock option compensation	$ 1.5	1.2
Stock Options Plan [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of stock vesting period	24 months
Stock Options Plan [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of stock vesting period	5 years
Stock Equivalent Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration term for stock granted	10 years
Fully vested stock options with performance conditions attached \| shares	28,881
Total intrinsic value exercised	$ 7.3	2.7	1.7
Expected compensation cost recognized over the weighted-average period	1 year 10 months 17 days
Accrued liabilities	$ 24.6
Number of exercisable SEUs \| shares	31,649
Compensation cost	$ 20.1	$ 5.7	$ 6.6
Stock Equivalent Units [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of stock vesting period	11 months
Stock Equivalent Units [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of stock vesting period	4 years

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Share based compensation arrangement by share based payment award options exercisable number performance conditions attached.

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Share-based compensation shares authorized under stock equivalent units exercise price range number of exercisable options.

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Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Amount of cost to be recognized for option under share-based payment arrangement.

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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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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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The number of shares reserved for issuance pertaining to the outstanding exercisable stock options as of the balance sheet date in the customized range of exercise prices for which the market and performance vesting condition has been satisfied.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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