Shareholders' Equity - Stock-based Compensation Expense (Benefit) (Details) - 2014 Incentive Plan - USD ($) $ in Millions	12 Months Ended
	May 02, 2020	Apr. 27, 2019	Apr. 28, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 0.3	$ 14.0	$ 4.0
Unrecognized equity-based compensation cost	0.0
RSAs | Executives and non-executive members of management
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	(2.1)	10.9	(2.0)
Unrecognized equity-based compensation cost	0.0
RSAs | Independent directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	0.9	0.9	1.0
Unrecognized equity-based compensation cost	0.0
RSUs | Executives and non-executive members of management
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1.5	$ 2.2	$ 5.0
Unrecognized equity-based compensation cost	$ 0.0