Business Combinations (Business Combination Pro Forma Information) (Details) (USD $)	3 Months Ended				6 Months Ended
	Apr. 30, 2012		Apr. 30, 2011		Apr. 30, 2012		Apr. 30, 2011
Business Acquisition [Line Items]
Revenue	$ 436,541,000	[1]	$ 431,709,000		$ 900,666,000	[1]	$ 831,118,000
Net Income	29,833,000	[2]	47,556,000	[2]	77,476,000	[2]	87,602,000	[2]
Magma Corporation [Member]
Business Acquisition [Line Items]
Revenue	13,500,000				13,500,000
Acquisition-related costs	$ 30,200,000				$ 31,800,000

[1] Revenues for the three and six months ended April 30, 2012 includes $13.5 million of revenues from Magma since the acquisition date.

[2] 2012 supplemental pro forma net income was adjusted to exclude $30.2 million and $31.8 million of acquisition-related costs during the three and six months ended April 30, 2012, respectively. Corresponding periods of 2011 supplemental pro forma net income were adjusted to include these charges. Disclosure of net income of Magma since the acquisition is impracticable due to the integration of Magma with the Company's operations.