CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Parent	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest	Total
Balance at Apr. 30, 2018	$ 409,033	$ 2	$ 170,139	$ 238,913	$ (21)	$ 23
Balance (in shares) at Apr. 30, 2018		23,908,736
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Apr. 30, 2018							$ 409,056
Increase (Decrease) in Stockholders' Equity
Net income	33,387			33,387		(21)	33,366
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest							33,366
Net (income) loss attributable to noncontrolling interest							21
Unrealized gain on investments	57				57		57
Foreign currency translation	(31)				(31)		(31)
Stock options exercised	71		71				71
Stock options exercised (in shares)		12,725
Restricted stock awards (in shares)		34,446
Restricted stock awards forfeited (in shares)		(14,655)
Tax withholding payment related to net share settlement of equity awards	(975)		(975)				(975)
Tax withholding payment related to net share settlement of equity awards (in shares)		(12,879)
Stock-based compensation	2,632		2,632				2,632
Balance at Oct. 27, 2018	444,174	$ 2	171,867	272,300	5	2
Balance (in shares) at Oct. 27, 2018		23,928,373
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Oct. 27, 2018							444,176
Balance at Jul. 28, 2018	437,050	$ 2	170,789	266,243	16	9
Balance (in shares) at Jul. 28, 2018		23,923,342
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Jul. 28, 2018							437,059
Increase (Decrease) in Stockholders' Equity
Net income	6,057			6,057		(7)	6,050
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest							6,050
Net (income) loss attributable to noncontrolling interest							7
Foreign currency translation	(11)				(11)		(11)
Stock options exercised	4		4				4
Stock options exercised (in shares)		6,725
Restricted stock awards (in shares)		1,034
Restricted stock awards forfeited (in shares)		(1,202)
Tax withholding payment related to net share settlement of equity awards	(156)		(156)				(156)
Tax withholding payment related to net share settlement of equity awards (in shares)		(1,526)
Stock-based compensation	1,230		1,230				1,230
Balance at Oct. 27, 2018	444,174	$ 2	171,867	272,300	5	2
Balance (in shares) at Oct. 27, 2018		23,928,373
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Oct. 27, 2018							444,176
Balance at Apr. 30, 2019	462,571	$ 2	176,216	286,351	2	4	462,571
Balance (in shares) at Apr. 30, 2019		23,946,293
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Apr. 30, 2019							462,575
Increase (Decrease) in Stockholders' Equity
Net income	24,611			24,611		(7)	24,604
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest							24,604
Net (income) loss attributable to noncontrolling interest							7
Foreign currency translation	179				179		179
Stock options exercised	93		93				93
Stock options exercised (in shares)		3,000
Restricted stock awards (in shares)		65,692
Restricted stock awards forfeited (in shares)		(11,005)
Tax withholding payment related to net share settlement of equity awards	(743)		(743)				(743)
Tax withholding payment related to net share settlement of equity awards (in shares)		(13,364)
Stock-based compensation	2,984		2,984				2,984
Balance at Oct. 26, 2019	490,360	$ 2	178,550	311,627	181	(3)	490,360
Balance (in shares) at Oct. 26, 2019		23,990,616
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Oct. 26, 2019							490,357
Balance at Jul. 27, 2019	481,506	$ 2	177,207	304,126	171	(7)
Balance (in shares) at Jul. 27, 2019		23,990,459
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Jul. 27, 2019							481,499
Increase (Decrease) in Stockholders' Equity
Net income	7,501			7,501		4	7,505
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest							7,505
Net (income) loss attributable to noncontrolling interest							(4)
Foreign currency translation	10				10		10
Restricted stock awards (in shares)		7,831
Restricted stock awards forfeited (in shares)		(6,285)
Tax withholding payment related to net share settlement of equity awards	(75)		(75)				(75)
Tax withholding payment related to net share settlement of equity awards (in shares)		(1,389)
Stock-based compensation	1,418		1,418				1,418
Balance at Oct. 26, 2019	490,360	$ 2	$ 178,550	311,627	$ 181	$ (3)	490,360
Balance (in shares) at Oct. 26, 2019		23,990,616
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Oct. 26, 2019							490,357
Increase (Decrease) in Stockholders' Equity
Adoption of ASU	$ 665			$ 665			$ 665