Fair Value of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Oct. 30, 2011	Apr. 30, 2011
Financial liabilities [Abstract]
Contingent consideration	$ (14,340)
Convertible Debt [Abstract]
Cost Method Investment, Number of Companies	3	3
Minority Investments [Abstract]
Minority investments	12,289	12,289
Balance at July 31, 2011	13,598
Accretion	742
Balance at October 30, 2011	14,340
Carrying Amount [Member]
Financial assets [Abstract]
Cash and cash equivalents	228,040	314,765
Equity method investment		31,142
Total	228,040	345,907
Financial liabilities [Abstract]
Convertible notes	40,015	40,015
Short-term debt	4,281
Contingent consideration	(14,340)
Total	58,636	40,015
Minority Investments [Abstract]
Balance at July 31, 2011
Balance at October 30, 2011	14,340
Fair Value [Member]
Financial assets [Abstract]
Cash and cash equivalents	228,040	314,765
Equity method investment		38,671
Total	228,040	353,436
Financial liabilities [Abstract]
Convertible notes	87,105	113,023
Short-term debt	4,281
Contingent consideration	(14,340)
Total	105,726	113,023
Minority Investments [Abstract]
Balance at July 31, 2011
Balance at October 30, 2011	14,340
Convertible Senior Notes Due 2029 (Fiscal Year 2030) [Member]
Convertible Debt [Abstract]
Interest Rate	5.00%	5.00%
Fair Value, Measurements, Recurring [Member]
Financial assets [Abstract]
Cash and cash equivalents	$ 228,040	$ 314,765