Fair Value of Financial Instruments - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $)
In Thousands, unless otherwise specified |
Apr. 30, 2013
|
Apr. 30, 2012
|
---|---|---|
Assets: | ||
Restricted assets | $ 545 | $ 424 |
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
|
||
Assets: | ||
Restricted assets | 545 | 424 |
Liabilities: | ||
Interest rate derivatives | ||
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
|
||
Assets: | ||
Restricted assets | ||
Liabilities: | ||
Interest rate derivatives | 4,229 | 2,369 |
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
|
||
Assets: | ||
Restricted assets | ||
Liabilities: | ||
Interest rate derivatives |