Interim Financial Statements - Out of Period Adjustments (Details) (Timing of Revenue Recognition [Member], USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended	12 Months Ended
	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2012	Jul. 31, 2012	Oct. 31, 2011	Oct. 31, 2010
Timing of Revenue Recognition [Member]
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Out of period revenue adjustments	$ 4.6
Prior period understated revenue		0.1	1.8		1.2	1.5
Cumulative effect of prior period revenue adjustments				$ 2.7