Discontinued Operations - Additional Information (Detail) - USD ($)			3 Months Ended	12 Months Ended
	Feb. 19, 2014	Oct. 21, 2013	Apr. 30, 2013	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of bus business		$ 100,000,000			$ 105,043,000
Discontinued operation, amounts collected from ASV	$ 5,043,000
Pre-tax gain (loss) on disposal of discontinued business					7,079,000
Goodwill impairment				$ 0	0	$ 0
Disposition of ambulance net assets			$ 12,051,000
Gain (loss) recognized on sale of assets			0
Impact of indemnification to tax expenses					$ 1,883,000
Buses
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Goodwill fair value				$ 0
Goodwill impairment			6,810,000
Impairment of goodwill and intangible assets			11,525,000
Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Amortizable intangible assets impairment charge			$ 4,715,000