Employee Benefits - Non-qualified Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 27, 2019	Apr. 28, 2018
Retirement and Welfare
Pension termination charge	$ 32,671
Non-qualified defined benefit retirement plan (not funded)
Retirement and Welfare
Total cost recognized	800	$ 800
Actuarial loss recognized in accumulated other comprehensive loss	200	200
Benefit payments	1,100	$ 1,100
Future benefit payments expected annually for the next ten years	$ 1,100
Discount rate used to determine benefit obligations (as a percent)	3.90%	4.10%
Non-qualified defined benefit retirement plan (not funded) | Other long-term liabilities
Retirement and Welfare
Plan obligations	$ 15,500	$ 15,500