Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
Apr. 27, 2019	Apr. 28, 2018	Apr. 29, 2017
Allowance for uncollectible accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 0.5	$ 0.6	$ 0.5
Charged to Costs and Expenses	0.2	0.0	0.1
Charged to Other Accounts— Describe	0.2	0.0	0.0
Deductions— Describe	0.0	0.1	0.0
Balance at End of Period	0.9	0.5	0.6
Deferred tax valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	2.5	1.9	1.3
Charged to Costs and Expenses	0.0	0.0	0.0
Charged to Other Accounts— Describe	4.8	0.0	0.0
Deductions— Describe	1.0	(0.6)	(0.6)
Balance at End of Period	$ 6.3	$ 2.5	$ 1.9

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

Amount of valuation and qualifying accounts and reserves.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09)
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690

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Amount of increase in valuation and qualifying accounts and reserves from charge to cost and expense.

+ References

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Amount of increase in valuation and qualifying accounts and reserves from charge to accounts other than cost and expense.

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Amount of decrease in valuation and qualifying accounts and reserves.

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