Capital Lease - Additional Information (Detail) (USD $)	1 Months Ended	9 Months Ended
	Oct. 28, 2011	Jan. 31, 2013 Installment	Apr. 30, 2012
Capital Leased Assets [Line Items]
Proceeds from lease of machinery and equipment	$ 3,500,000
Effective interest rate	5.76%
Number of monthly installments		60
Condition of lease qualifies as capital lease		Net present value of future lease payments exceed 90% of the fair market value of the leased machinery and equipment
Percentage of fair market value for qualifying as capital lease		90.00%
Current portion of capital lease obligation		436,000	418,000
Amount of short term capital lease obligations in other non current liabilities		$ 2,500,000