Common Stock Repurchase Program (Detail) - USD ($)	12 Months Ended
	May 03, 2020	Apr. 28, 2019	Apr. 29, 2018	Sep. 05, 2019
Stockholders Equity Note [Line Items]
Cost of common stock repurchase	$ 1,680,000	$ 3,323,000
Common Stock [Member]
Stockholders Equity Note [Line Items]
Common stock repurchased	142,496	160,823
Cost of common stock repurchase	$ 7,000	$ 8,000
Remaining authorized repurchase amount	$ 5,000,000
Stock Repurchase Program September 5, 2019 [Member] | Common Stock [Member]
Stockholders Equity Note [Line Items]
Authorization amount for repurchase of common stock				$ 5,000,000
Common stock repurchased	142,496
Cost of common stock repurchase	$ 1,700,000
Remaining authorized repurchase amount				$ 3,300,000
Stock Repurchase Program March 2020 [Member] | Common Stock [Member]
Stockholders Equity Note [Line Items]
Authorization amount for repurchase of common stock	$ 5,000,000
Stock Repurchase Program June 15, 2016 [Member] | Common Stock [Member]
Stockholders Equity Note [Line Items]
Common stock repurchased		160,823	0
Cost of common stock repurchase		$ 3,300,000