Stockholders Equity - Income Tax Benefits Associated with Employee Stock Transactions (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
Jan. 25, 2013	Jan. 27, 2012
Deferred Income Taxes And Tax Credits [Line Items]
Income tax benefit associated with employee stock transactions	$ 35.4	$ 74.7

Adjustment to additional paid in capital related to the net effect of excess tax benefits and tax deficiencies associated with an equity-based compensation plan other than an employee stock ownership plan (ESOP).

No definition available.

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