Summary of Significant Accounting Policies - Reconciliation of Weighted Average Common Shares Used to Calculate Basic Net Income Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2013	Oct. 31, 2014		Oct. 31, 2013		Oct. 31, 2012
Earnings Per Share [Abstract]
Net income	$ 62,455	$ 65,656	$ 63,317	$ 67,696	$ 56,890	$ 52,297	$ 68,691	$ 69,922	$ 259,124		$ 247,800		$ 182,402
Weighted average common shares for basic net income per share									155,054		153,319		146,887
Dilutive effect of common share equivalents from equity—based compensation									2,656		3,282		3,393
Weighted average common shares for diluted net income per share									157,710		156,601		150,280
Basic (in dollars per share)	$ 0.40	$ 0.42	$ 0.41	$ 0.44	$ 0.37	$ 0.34	$ 0.45	$ 0.46	$ 1.67		$ 1.62		$ 1.24
Diluted (in dollars per share)	$ 0.39	$ 0.42	$ 0.40	$ 0.43	$ 0.36	$ 0.33	$ 0.44	$ 0.45	$ 1.64		$ 1.58		$ 1.21
Anti-dilutive employee stock-based awards excluded									2,196	[1]	1,326	[1]	3,314	[1]

[1] These stock options and unvested restricted stock units were anti-dilutive for the respective periods and are excluded in calculating diluted net income per share. While such awards were anti-dilutive for the respective periods, they could be dilutive in the future.