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Schedule of Other Current Assets (Parenthetical) (Detail) - USD ($) $ in Millions	Apr. 30, 2018	Dec. 31, 2017
Former CEO | Scenario, Forecast
Schedule Of Other Current Assets [Line Items]
Payment advances of lump sum benefit	$ 9.6
Rabbi Trust
Schedule Of Other Current Assets [Line Items]
Investments liquidation value		$ 8.9

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- Definition

Investments liquidation value.

+ References

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- Definition

Payment advances of lump sum benefit.

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+ Details

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- Definition

Schedule of other current assets.

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