Discontinued Operations - Additional Information (Detail) (USD $)	1 Months Ended		3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended		3 Months Ended
	Feb. 19, 2014	Oct. 21, 2013	Apr. 30, 2013	Apr. 30, 2014	Apr. 30, 2013 Buses	Apr. 30, 2013 Buses	Apr. 30, 2014 Buses	Apr. 30, 2014 Discontinued Operations
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 on sale of business				7,079,000
Amortizable intangible assets impairment charge								4,715,000
Goodwill fair value							0
Third quarter impairment				0	6,810,000
Impairment of goodwill and intangible assets						11,525,000
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