Benefit Plans	12 Months Ended
Apr. 30, 2012
Benefi Plans [Abstract]
Benefit Plans	8. Benefit plans 401(k) plan The Company provides employees with a defined contribution 401(k) plan. The 401(k) plan covers all employees who meet minimum age and service requirements. The Company contributions consist of matching amounts and are allocated based on employee contributions. Contributions to the 401(k) plan were $3,681, $3,049, and $2,964 for the years ended April 30, 2012, 2011, and 2010, respectively. On April 30, 2012, 1,520,985 shares of common stock were held by the trustee of the 401(k) plan in trust for distribution to eligible participants upon death, disability, retirement, or termination of employment. Shares held by the 401(k) plan are treated as outstanding in the computation of earnings per common share. Supplemental executive retirement plan The Company has a nonqualified supplemental executive retirement plan (SERP) for 2 of its executive officers, 1 of whom retired April 30, 2003 and the other on April 30, 2008. The SERP provides for the Company to pay annual retirement benefits, depending on retirement dates, up to 50% of base compensation until death of the officer. If death occurs within twenty years of retirement, the benefits become payable to the officer’s spouse until the spouse’s death or twenty years from the date of the officer’s retirement, whichever comes first. The Company has accrued the deferred compensation over the term of employment. The amounts accrued at April 30, 2012 and 2011, respectively, were $6,611 and $6,574. The discount rates used were 4.6% and 5.5%, respectively, at April 30, 2012 and 2011. The amount expensed in fiscal 2012 was $662. The Company expects to pay $625 per year for each of the next five years. There was no expense incurred in fiscal 2011 or 2010.

401(k) plan The Company provides employees with a defined contribution 401(k) plan. The 401(k) plan covers all employees who meet minimum age and service requirements. The Company contributions consist of matching amounts and are allocated based on employee contributions. Contributions to the 401(k) plan were $3,681, $3,049, and $2,964 for the years ended April 30, 2012, 2011, and 2010, respectively.

On April 30, 2012, 1,520,985 shares of common stock were held by the trustee of the 401(k) plan in trust for distribution to eligible participants upon death, disability, retirement, or termination of employment. Shares held by the 401(k) plan are treated as outstanding in the computation of earnings per common share.

Supplemental executive retirement plan The Company has a nonqualified supplemental executive retirement plan (SERP) for 2 of its executive officers, 1 of whom retired April 30, 2003 and the other on April 30, 2008. The SERP provides for the Company to pay annual retirement benefits, depending on retirement dates, up to 50% of base compensation until death of the officer. If death occurs within twenty years of retirement, the benefits become payable to the officer’s spouse until the spouse’s death or twenty years from the date of the officer’s retirement, whichever comes first. The Company has accrued the deferred compensation over the term of employment. The amounts accrued at April 30, 2012 and 2011, respectively, were $6,611 and $6,574. The discount rates used were 4.6% and 5.5%, respectively, at April 30, 2012 and 2011. The amount expensed in fiscal 2012 was $662. The Company expects to pay $625 per year for each of the next five years. There was no expense incurred in fiscal 2011 or 2010.