Changes in Each Component of Accumulated Other Comprehensive (Loss) Income (Parenthetical) (Detail) - USD ($) $ in Thousands |
12 Months Ended | ||
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Apr. 30, 2017 |
Apr. 30, 2016 |
Apr. 30, 2015 |
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| Accumulated Other Comprehensive Income (Loss) [Line Items] | |||
| Tax effect on reclassifications of realized net losses | $ 1,200 | $ 1,100 | $ 1,200 |
| Tax effects on unrealized (losses) gains | 1,900 | $ (2,300) | $ (2,300) |
| Tax effect on unrealized (losses) | $ (406) | ||
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- Definition 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. No definition available.
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- Definition Amount of tax (expense) benefit, before reclassification adjustments, related to (increase) decrease in accumulated other comprehensive (income) loss related to pension and other postretirement benefit plans. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Amount of tax (expense) benefit of reclassification adjustment from accumulated other comprehensive (income) loss related to pension and other postretirement defined benefit plans. No definition available.
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- Definition Amount of tax expense (benefit), before reclassification adjustments, related to increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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