Business Segment Information - Additional Information (Detail) (USD $)	3 Months Ended			12 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Oct. 31, 2011	Jul. 31, 2013 Segment	Jul. 31, 2012	Jul. 31, 2011
Segment Reporting Information [Line Items]
Number of reportable segments				3
Gain from settlement of litigation				$ 9,251,000	$ (6,698,000)
Other operating losses				9,251,000	(15,870,000)	2,824,000
Estimated losses from pending litigation		6,500,000
Gain (loss) from settlement of litigation	9,600,000		(11,000,000)		(11,022,000)
Loss on settlement of unrelated claim					200,000
Termination expense						14,375,000
Patent expense						10,828,000
Gain (loss) on settlement of other claims						(2,860,000)
Insurance claims						2,637,000
Telecom Platform Services [Member]
Segment Reporting Information [Line Items]
Gain from settlement of litigation				9,300,000
Other operating losses					(15,900,000)
Estimated losses from pending litigation					6,500,000
Termination expense						14,400,000
Patent expense						10,800,000
All Other [Member]
Segment Reporting Information [Line Items]
Gain (loss) on settlement of other claims						(2,900,000)
Insurance claims						2,600,000
Broadstripe, LLC [Member]
Segment Reporting Information [Line Items]
Gain (loss) from settlement of litigation					1,800,000
T-Mobile [Member]
Segment Reporting Information [Line Items]
Gain (loss) from settlement of litigation					$ (11,000,000)