Organization and Summary of Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified	Oct. 31, 2013	Apr. 30, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 3,084	$ 6,312
Securities available-for-sale	7,966	6,682
Investments, fair value disclosure	11,050	12,994
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	3,084	6,312
Securities available-for-sale	7,966	6,682
Investments, fair value disclosure	11,050	12,994
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents
Securities available-for-sale
Investments, fair value disclosure
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents
Securities available-for-sale
Investments, fair value disclosure