v2.4.0.6
Income Taxes (Narrative) (Details) (USD $)
 0 Months Ended 3 Months Ended 12 Months Ended 3 Months Ended 12 Months Ended
Jan. 31, 2010
Apr. 30, 2011
Oct. 31, 2011
Oct. 31, 2010
Oct. 31, 2009
Oct. 31, 2010
Avant! Corporation [Member]
Jan. 31, 2011
Synplicity, Inc. [Member]
Oct. 31, 2010
Increase Net [Member]
Income Taxes [Line Items]                
Decrease in valuation allowance     $ 1,300,000          
Unrecognized deferred tax assets     36,800,000          
Undistributed foreign earnings     530,000,000          
Tax on deferred undistributed foreign earnings     114,000,000          
Decrease in gross unrecognized tax benefits     36,000,000          
Gross unrecognized tax benefits     177,893,000 213,923,000 253,861,000      
Unrecognized tax benefits affecting effective tax rate     177,000,000 202,000,000        
The sum of the amounts of estimated penalties and interest recognized in the period arising from income tax examinations     2,800,000 3,400,000 2,000,000      
The amount of estimated penalties and interest accrued as of the balance sheet date arising from income tax examinations     7,400,000 7,300,000        
Estimated potential decrease in underlying unrecognized tax benefits, minimum     0          
Estimated potential decrease in underlying unrecognized tax benefits, maximum     110,000,000          
Income tax examination years audit of its fiscal years 2002 through 2004 IRS for its audits of fiscal years 2006 through 2009   audit of its fiscal years 2002 through 2004       audit of its fiscal years 2002 through 2004
Decrease in unrecognized tax benefits resulting from settlement with the IRS     (1,258,000) (14,962,000)   67,800,000 4,000,000  
Unrecognized tax benefits decreases resulting from settlements with US taxing authorities   35,900,000            
Tax impact of final settlement with IRS   32,800,000       94,300,000    
Release of valuation allowance           21,600,000    
Tax adjustments settlements and unusual provisions       72,300,000       55,400,000
Decrease in deferred tax assets due to utilization of foreign tax credit carryover net of reversal of valuation allowance       $ 25,200,000        
Penalties imposed on the amount of additional tax     50.00%