Supplementary Data - Selected Unaudited Quarterly Financial Data (Details) (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
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 539,012	$ 521,812	$ 517,697	$ 478,951	$ 504,875	$ 482,945	$ 499,257	$ 475,137	$ 2,057,472	$ 1,962,214	$ 1,756,017
Gross margin	417,591	406,282	403,612	373,102	385,766	367,298	391,524	364,074	1,600,587	1,508,662	1,363,344
Income before provision for income taxes	62,128	70,771	68,059	71,184	59,057	58,172	86,707	71,730	272,142	275,666	201,135
Net income	$ 62,455	$ 65,656	$ 63,317	$ 67,696	$ 56,890	$ 52,297	$ 68,691	$ 69,922	$ 259,124	$ 247,800	$ 182,402
Net income per share
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