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Significant Accounting Policies - Noncurrent Deferred Tax Assets Recorded in Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020
Equity [Abstract] |  |  |  |
Balance at beginning of period, Pension and Postretirement Benefit Plans | $ 87.9 | $ 83.6 | $ 89.4 | $ 85.2
Tax effect of other comprehensive earnings, Pension and Postretirement Benefit Plans | (0.8) | (1.1) | (2.3) | (2.7)
Balance at end of period, Pension and Postretirement Benefit Plans | $ 87.1 | $ 82.5 | $ 87.1 | $ 82.5

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- Definition Accumulated other comprehensive loss, noncurrent deferred tax assets, other comprehensive earnings, tax effect, pension and postretirement benefit plans. + References No definition available. + Details
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- Definition Accumulated other comprehensive loss, noncurrent deferred tax assets, pension and postretirement benefit plans. + References No definition available. + Details
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- References No definition available. + Details
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