Net Income per Share - Schedule of Antidilutive Securities Excluded from Computation of Net Income (Loss) per Share (Details) - shares
shares in Thousands
 3 Months Ended 9 Months Ended
Jan. 31, 2016
Jan. 25, 2015
Jan. 31, 2016
Jan. 25, 2015
Dec. 31, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share          
Antidilutive securities excluded from computation of earnings per share 5,287 1,170 3,124 3,575  
Stock Options and Restricted Stock Units          
Antidilutive Securities Excluded from Computation of Earnings Per Share          
Antidilutive securities excluded from computation of earnings per share 5,287 1,170 3,124 1,062  
Convertible Debt | 5.0% Convertible Senior Notes Due 2029          
Antidilutive Securities Excluded from Computation of Earnings Per Share          
Interest rate 5.00% 5.00% 5.00% 5.00%  
Convertible Debt | 5.0% Convertible Senior Notes Due 2029 | Convertible Debt Securities          
Antidilutive Securities Excluded from Computation of Earnings Per Share          
Antidilutive securities excluded from computation of earnings per share 0 0 0 2,513  
Convertible Debt | 0.5% Convertible Senior Notes Due 2033          
Antidilutive Securities Excluded from Computation of Earnings Per Share          
Interest rate 0.50% 0.50% 0.50% 0.50% 0.50%
Convertible Debt | 0.5% Convertible Senior Notes Due 2033 | Convertible Debt Securities          
Antidilutive Securities Excluded from Computation of Earnings Per Share          
Antidilutive securities excluded from computation of earnings per share [1] 0 0 0 0  
[1] 0.50% Convertible Senior Notes due 2033 were excluded from the calculation of diluted earnings per share under the treasury stock method since the conversion price exceeded the average market price for the Company's common stock.