Stock Based Compensation - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Oct. 31, 2014	Oct. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, Grants in Period	612,427
Shares authorized	4,620,662
Shares reserved for future issuance	3,325,301
Share-based compensation expense	$ 1,319	$ 2,600
Share-based compensation expense (net of tax)	818	1,586
Unrealized compensation cost related to share-based compensation, pre tax	11,425
Weighted average period remaining	2 years 7 months 30 days
Options outstanding, exercisable	3,339,992	3,466,777
Options Exercisable, Weighted Average Exercise Price	$ 30.94	$ 30.93
Proceeds from stock options exercised	91	5,209
Tax benefit on options exercised	3	472
Intrinsic value of options exercised	7	1,211
Fair value of options vested	$ 3,684	$ 8,383
Options, Grants in Period, Weighted Average Exercise Price	$ 22.66	$ 31.07
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 6.10	$ 9.18
Service Based Restricted Shares and Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs and Restricted Shares, Grants in Period	224,398
RSUs and Restricted Shares, Grants in Period, Weighted Average Grant Date Fair Value	$ 23.45