Fair Value Measurements - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Jul. 31, 2014	Jul. 31, 2013
Fair Value Assets Liabilities Quantitative Information [Line Items]
Investments in hedge funds	$ 9.5	$ 8.3
Carrying value of investments	1.8	1.5
Other Current Assets [Member]
Fair Value Assets Liabilities Quantitative Information [Line Items]
Investments in hedge funds	0.1	0.1
Long-term Investments [Member]
Fair Value Assets Liabilities Quantitative Information [Line Items]
Investments in hedge funds	$ 9.4	$ 8.2