Retirement and Welfare (Details) (USD $)	12 Months Ended
	Apr. 26, 2014		Apr. 27, 2013		Apr. 28, 2012
Defined Benefit Plan Disclosure [Line Items]
Amount of obligations under performance compensation retirement plan	$ 2,500,000
Deferred compensation arrangement obligations	12,300,000		10,000,000
Cash surrender value of life insurance contracts and mutual funds	10,900,000		8,900,000
Market value of mutual funds included in other current assets	1,800,000		1,100,000
Interest cost	4,822,000		5,325,000		5,565,000
Benefits paid	9,123,000		9,586,000
Defined benefit plan amounts recognized in other comprehensive income (loss) [Abstract]
Beginning of year net actuarial loss	48,745,000		45,270,000
Net current year actuarial (gain) loss	(5,932,000)		6,499,000
Amortization of actuarial loss	(3,388,000)		(3,024,000)
End of year net actuarial loss	39,425,000		48,745,000		45,270,000
Expect to amortize of unrecognized actuarial losses	2,700,000
Components of net periodic benefit cost [Abstract]
Service cost	1,241,000		1,231,000		1,110,000
Interest cost	4,822,000		5,325,000		5,565,000
Expected return on plan assets	(6,800,000)		(6,855,000)		(6,820,000)
Net amortization and deferral	3,388,000		3,024,000		1,635,000
Net periodic pension cost (hourly plan)	2,651,000		2,725,000		1,490,000
401(k)	5,802,000	[1]	5,198,000	[1]	2,473,000	[1]
PCRP	2,513,000	[1]	0	[1]	0	[1]
Other	223,000	[1]	191,000	[1]	107,000	[1]
Total retirement costs (excluding non-qualified defined benefit retirement plan)	11,189,000		8,114,000		4,070,000
Change in benefit obligation [Roll Forward]
Benefit obligation at beginning of year	123,495,000		118,347,000
Service cost	1,241,000		1,231,000		1,110,000
Interest cost	4,822,000		5,325,000		5,565,000
Actuarial (gain) loss	(3,565,000)		8,178,000
Benefits paid	(9,123,000)		(9,586,000)
Benefit obligation at end of year	116,870,000		123,495,000		118,347,000
Change in Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	111,430,000		89,002,000
Actual return on plan assets	9,494,000		9,060,000
Employer contributions	0		23,480,000
Other expenses	(327,000)		(526,000)
Benefits paid	(9,123,000)		(9,586,000)
Fair value of plan assets at end of year	111,474,000		111,430,000		89,002,000
Funded status	(5,396,000)		(12,065,000)
Actuarial assumptions defined benefit pension plan [Abstract]
Discount rate used to determine benefit obligations (in hundredths)	4.40%		4.00%		4.60%
Discount rate used to determine net benefit cost (in hundredths)	4.00%		4.60%		5.60%
Long-term rate of return (in hundredths)	4.70%		6.30%		7.80%
Defined Benefit Plan, Expected future benefit payments, fiscal year maturity [Abstract]
2015	5,574,000
2016	5,625,000
2017	5,772,000
2018	5,906,000
2019	6,077,000
2020 to 2024	33,253,000
Total	62,207,000
Level 1 [Member]
Change in Plan Assets [Roll Forward]
Fair value of plan assets at end of year	22,830,000	[2]	47,476,000	[3]
Level 2 [Member]
Change in Plan Assets [Roll Forward]
Fair value of plan assets at end of year	88,644,000	[2]	63,954,000	[3]
Level 3 [Member]
Change in Plan Assets [Roll Forward]
Fair value of plan assets at end of year	0		0
Equity Securities [Member] | Level 1 [Member]
Change in Plan Assets [Roll Forward]
Fair value of plan assets at end of year	22,623,000	[2]	47,047,000	[3]
Equity Securities [Member] | Level 2 [Member]
Change in Plan Assets [Roll Forward]
Fair value of plan assets at end of year	7,736,000	[2]	16,140,000	[3]
Equity Securities [Member] | Level 3 [Member]
Change in Plan Assets [Roll Forward]
Fair value of plan assets at end of year	0		0
Fixed Income [Member]
Actuarial assumptions defined benefit pension plan [Abstract]
Strategic asset allocation (in hundredths)	90.00%
Cash and Equivalents [Member] | Level 1 [Member]
Change in Plan Assets [Roll Forward]
Fair value of plan assets at end of year	207,000	[2]	429,000	[3]
Cash and Equivalents [Member] | Level 2 [Member]
Change in Plan Assets [Roll Forward]
Fair value of plan assets at end of year	6,083,000	[2]	15,767,000	[3]
Cash and Equivalents [Member] | Level 3 [Member]
Change in Plan Assets [Roll Forward]
Fair value of plan assets at end of year	0		0
Debt Securities [Member] | Level 1 [Member]
Change in Plan Assets [Roll Forward]
Fair value of plan assets at end of year	0	[2]	0	[3]
Debt Securities [Member] | Level 2 [Member]
Change in Plan Assets [Roll Forward]
Fair value of plan assets at end of year	74,825,000	[2]	32,047,000	[3]
Debt Securities [Member] | Level 3 [Member]
Change in Plan Assets [Roll Forward]
Fair value of plan assets at end of year	0		0
Factory Hourly Employees [Member]
Defined Benefit Plan Disclosure [Line Items]
Other long-term liabilities	(5,396,000)		(12,065,000)
Non-Qualified Defined Benefit Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Other long-term liabilities	(16,200,000)		(17,000,000)
Interest cost	800,000		800,000
Actuarial gain (loss) recognized in accumulated other comprehensive loss	400,000		1,100,000
Benefits paid	1,100,000		1,100,000
Expected future benefit payments annually in next ten years	1,100,000
Components of net periodic benefit cost [Abstract]
Interest cost	800,000		800,000
Change in benefit obligation [Roll Forward]
Interest cost	800,000		800,000
Benefits paid	(1,100,000)		(1,100,000)
Change in Plan Assets [Roll Forward]
Benefits paid	$ (1,100,000)		$ (1,100,000)
Actuarial assumptions defined benefit pension plan [Abstract]
Discount rate used to determine benefit obligations (in hundredths)	4.30%		3.70%

[1] Not determined by an actuary

[2] There were no transfers between Level 1 and Level 2 during fiscal 2014.

[3] There were no transfers between Level 1 and Level 2 during fiscal 2013.