Calculations of Basic and Diluted Net Income per Common Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Oct. 31, 2011		Jul. 31, 2011		Apr. 30, 2011		Jan. 31, 2011		Oct. 31, 2010		Jul. 31, 2010		Apr. 30, 2010		Jan. 31, 2010		Oct. 31, 2011		Oct. 31, 2010		Oct. 31, 2009
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Income from continuing operations	$ 18,182		$ 27,911		$ 14,200		$ 8,405		$ 21,438		$ 20,973		$ 8,623		$ 12,836		$ 68,698		$ 63,870		$ 55,490
(Loss) income from discontinued operations, net of taxes	(135)		(36)		(8)		(15)		368		(10)		(46)		(61)		(194)		251		(1,197)
Net income	$ 18,047		$ 27,875		$ 14,192		$ 8,390		$ 21,806		$ 20,963		$ 8,577		$ 12,775		$ 68,504		$ 64,121		$ 54,293
Weighted-average common shares outstanding-Basic																	53,121		52,117		51,373
Effect of dilutive securities:
Weighted-average common shares outstanding-Diluted																	54,103		52,908		51,845
Net income per common share
Basic	$ 0.34	[1]	$ 0.52	[1]	$ 0.27	[1]	$ 0.16	[1]	$ 0.42	[1]	$ 0.40	[1]	$ 0.16	[1]	$ 0.25	[1]	$ 1.29	[1]	$ 1.23	[1]	$ 1.06
Diluted	$ 0.33	[1]	$ 0.51	[1]	$ 0.26	[1]	$ 0.16	[1]	$ 0.41	[1]	$ 0.40	[1]	$ 0.16	[1]	$ 0.24	[1]	$ 1.27	[1]	$ 1.21	[1]	$ 1.05
Stock options
Effect of dilutive securities:
Effect of dilutive securities																	468		446		241
Restricted stock units
Effect of dilutive securities:
Effect of dilutive securities																	293		261		180
Performance shares
Effect of dilutive securities:
Effect of dilutive securities																	221		84		51

[1] The sum of the quarterly per share amounts may not equal per share amounts reported for the year-to-date periods, due to the effects of rounding for each period.