Taxes - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended	3 Months Ended
Jul. 31, 2014	Jul. 31, 2014	Jan. 31, 2014 IRS Fiscal Year 2012	Apr. 30, 2014 Taiwan Fiscal Year 2009 and 2010
Taxes [Line Items]
Statutory federal income tax rate	35.00%	35.00%
Gross unrecognized tax benefits	$ 102.9	$ 102.9
Unrecognized tax benefits that would affect effective tax rate	99.3	99.3
Estimated potential decrease in underlying unrecognized tax benefits, minimum	0	0
Estimated potential decrease in underlying unrecognized tax benefits, maximum	23	23
Unrecognized tax benefits decrease resulting from settlement			10.0	5.1
Tax impact from tax settlements				$ 3.9

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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The estimated lower bound of the reasonably possible change in the total amount of the unrecognized tax benefit (that will significantly increase or decrease within twelve months of the balance sheet date) for a tax position taken.

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The estimated upper bound of the reasonably possible change in the total amount of the unrecognized tax benefit (that will significantly increase or decrease within twelve months of the balance sheet date) for a tax position taken.

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Amount of increase (decrease) to previously recorded tax expense. Includes, but is not limited to, significant settlements of income tax disputes, and unusual tax positions or infrequent actions taken by the entity, including tax assessment reversal, and IRS tax settlement.

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Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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