Commitments and Contingencies - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended		6 Months Ended			1 Months Ended	6 Months Ended	12 Months Ended
	Mar. 31, 2013 sqft	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2013	Jul. 31, 2012	Jan. 31, 2013	May 31, 2013 2017 [Member]	Jul. 31, 2013 Indemnification Agreement [Member]	Jan. 31, 2013 Indemnification Agreement [Member]
Commitments And Contingencies [Line Items]
Net operating lease expenses		$ 1,300,000	$ 1,000,000	$ 2,400,000	$ 2,100,000
Lease agreement rental area in square feet	35,000
Initial lease term	5 years
Lease termination year	2018-04
Monthly basic rent obligation		44,550					65,400
Average monthly basic rent expense		59,800
Total manufacturing purchase commitments		17,600,000		17,600,000		15,100,000
Payments under indemnification obligations								0	0
Liabilities recorded under indemnification obligations								$ 0	$ 0