Stock-Based Compensation - Expense (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Oct. 26, 2019	Oct. 27, 2018	Oct. 26, 2019	Oct. 27, 2018
Stock-based compensation expense recognized for outstanding grants
Equity-based awards expense	$ 3,032	$ 3,639	$ 4,707	$ 5,679
Liability-based awards expense	400	(300)	340	(134)
Total stock-based compensation expense	$ 3,432	$ 3,339	$ 5,047	$ 5,545

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5047-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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