Components of Net Periodic Benefit Costs (Detail) - Deferred Compensation Plan - USD ($) $ in Thousands |
3 Months Ended | |
|---|---|---|
Jul. 31, 2015 |
Jul. 31, 2014 |
|
| Defined Benefit Plan Disclosure [Line Items] | ||
| Amortization of actuarial loss | $ 731 | $ 763 |
| Interest cost | 703 | 747 |
| Net periodic benefit costs | $ 1,434 | $ 1,510 |
| X | ||||||||||
- Definition The amount of gains or losses recognized in net periodic benefit cost. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- 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.
|
| X | ||||||||||
- Definition The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition The total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Details
|