Defined Benefit Pension Plans - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 13.6	$ 10.8	$ 8.9
Net periodic pension costs	0.1
Minimum required contributions to the plan	0.8
Defined benefit plans Assets Percentage invested in bank-managed portfolios	100.00%
Current target allocations for plan assets for debt securities	100.00%
Market value of plan assets using Level 2 inputs	$ 14.1
Cumulative gains and losses in excess of the greater of the pension benefit obligation	10.00%
Netherlands [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of pension plans	2
Taiwan [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of pension plans	1