Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended
Jan. 25, 2020	Jan. 26, 2019	Jan. 25, 2020	Jan. 26, 2019	Apr. 27, 2019
Fair Value Disclosures [Abstract]
Gain on investment	$ 0	$ 0	$ 34,334,000	$ 4,477,000
carrying value of investments	51,628,000		51,628,000		$ 17,294,000
Impairment charge		$ 0
Estimated fair value of debt	605,122,000		605,122,000		758,121,000
Carrying value of debt	$ 587,455,000		$ 587,455,000		$ 749,316,000

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Amount of realized and unrealized gain (loss) on investment.

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Sum of the carrying amounts as of the balance sheet date of all investments.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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