Stock-Based Compensation, Restricted Shares and RSUs (Details) (USD $)	12 Months Ended			3 Months Ended
	Apr. 25, 2015	Apr. 26, 2014	Apr. 27, 2013	Jul. 26, 2014
Stock-Based Compensation
Expense recognized	$ 11,377,000	$ 14,475,000	$ 13,628,000
Restricted Stock
Stock-Based Compensation
Percentage vesting each year from date of grant	25.00%
Period from grant date for first vesting	1 year
Vesting period	4 years
Unrecognized compensation cost	2,200,000
Period for recognition of unrecognized compensation costs	3 years 2 months 12 days
Number of Shares
Non-vested at beginning of period (in shares)	102,000			102,000
Granted (in shares)	115,811
Vested (in shares)	(66,000)
Canceled (in shares)	(10,000)
Non-vested at end of period (in shares)	142,000
Weighted Average Grant Date Fair Value
Non-vested at beginning of period (in dollars per share)	$ 7.77			$ 7.77
Granted (in dollars per share/unit)	$ 23.68			$ 23.63
Vested (in dollars per share)	$ 6.92
Canceled (in dollars per share)	$ 17.68
Non-vested at end of period (in dollars per share)	$ 20.50
Restricted Stock | Selling, General and Administrative Expense
Stock-Based Compensation
Expense recognized	800,000	500,000	1,000,000
Restricted Stock Units | Employees
Stock-Based Compensation
Fair value (in dollars per unit)	$ 27.49
Award common share equivalent (in shares)	1
Percentage vesting each year from date of grant	25.00%
Period from grant date for first vesting	1 year
Vesting period	4 years
Unrecognized compensation cost	2,700,000
Period for recognition of unrecognized compensation costs	1 year 9 months 18 days
Number of Shares
Non-vested at beginning of period (in shares)	221,000			221,000
Vested (in shares)	(63,000)
Canceled (in shares)	(12,000)
Non-vested at end of period (in shares)	146,000
Weighted Average Grant Date Fair Value
Non-vested at beginning of period (in dollars per share)	$ 15.90			$ 15.90
Vested (in dollars per share)	$ 15.35
Canceled (in dollars per share)	$ 16.14
Non-vested at end of period (in dollars per share)	$ 16.12
Restricted Stock Units | Directors
Number of Shares
Granted (in shares)	33,000
Weighted Average Grant Date Fair Value
Granted (in dollars per share/unit)	$ 21.81	$ 21.20	$ 13.99
Restricted Stock Units | Directors | Maximum
Number of Shares
Granted (in shares)	100,000	100,000	100,000
Restricted Stock Units | Selling, General and Administrative Expense | Employees
Stock-Based Compensation
Expense recognized	1,500,000	1,600,000	500,000
Restricted Stock Units | Selling, General and Administrative Expense | Directors
Stock-Based Compensation
Expense recognized	$ 700,000	$ 700,000	$ 700,000