Fair Value of Financial Instruments - Additional Information (Detail) (USD $)	Oct. 31, 2013	Apr. 30, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity method investment valued	$ 269,000	$ 271,000
Held-to-maturity investments	$ 0	$ 226,000

Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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Balance Type:	debit
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