Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Parent	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Non-controlling 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 (loss)	41,756			41,756		(40)	41,716
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest							41,716
Unrealized gain on investments	57				57		57
Foreign currency translation	(32)				(32)		(32)
Stock options exercised	71		71				71
Stock options exercised (in shares)		12,725
Restricted stock awards (in shares)		39,823
Restricted stock awards forfeited (in shares)		(15,100)
Tax withholding payment related to net share settlement of equity awards	(1,033)		(1,033)				(1,033)
Tax withholding payment related to net share settlement of equity awards (in shares)		(13,724)
Stock-based compensation	5,714		5,714				5,714
Balance at Jan. 26, 2019	455,566	$ 2	174,891	280,669	4	(17)
Balance (in shares) at Jan. 26, 2019		23,932,460
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Jan. 26, 2019							455,549
Balance at Oct. 27, 2018	444,174	$ 2	171,867	272,300	5	2	444,176
Balance (in shares) at Oct. 27, 2018		23,928,373
Increase (Decrease) in Stockholders' Equity
Net income (loss)	8,369			8,369		(19)	8,350
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest							8,350
Foreign currency translation	(1)				(1)		(1)
Restricted stock awards (in shares)		5,377
Restricted stock awards forfeited (in shares)		(445)
Tax withholding payment related to net share settlement of equity awards	(58)		(58)				(58)
Tax withholding payment related to net share settlement of equity awards (in shares)		(845)
Stock-based compensation	3,082		3,082				3,082
Balance at Jan. 26, 2019	455,566	$ 2	174,891	280,669	4	(17)
Balance (in shares) at Jan. 26, 2019		23,932,460
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Jan. 26, 2019							455,549
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 (loss)	23,603			23,603		(27)	23,576
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest							23,576
Foreign currency translation	67				67		67
Stock options exercised	93		93				93
Stock options exercised (in shares)		3,000
Restricted stock awards (in shares)		74,892
Restricted stock awards forfeited (in shares)		(11,769)
Tax withholding payment related to net share settlement of equity awards	(1,009)		(1,009)				(1,009)
Tax withholding payment related to net share settlement of equity awards (in shares)		(17,307)
Stock-based compensation	4,751		4,751				4,751
Balance at Jan. 25, 2020	490,741	$ 2	180,051	310,619	69	(23)	490,741
Balance (in shares) at Jan. 25, 2020		23,995,109
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Jan. 25, 2020							490,718
Balance at Oct. 26, 2019	490,360	$ 2	178,550	311,627	181	(3)
Balance (in shares) at Oct. 26, 2019		23,990,616
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Oct. 26, 2019							490,357
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(1,008)			(1,008)		(20)	(1,028)
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest							(1,028)
Foreign currency translation	(112)				(112)		(112)
Restricted stock awards (in shares)		9,200
Restricted stock awards forfeited (in shares)		(764)
Tax withholding payment related to net share settlement of equity awards	(266)		(266)				(266)
Tax withholding payment related to net share settlement of equity awards (in shares)		(3,943)
Stock-based compensation	1,767		1,767				1,767
Balance at Jan. 25, 2020	490,741	$ 2	$ 180,051	310,619	$ 69	$ (23)	490,741
Balance (in shares) at Jan. 25, 2020		23,995,109
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Jan. 25, 2020							490,718
Increase (Decrease) in Stockholders' Equity
Adoption of ASU | ASU 2018-09	$ 665			$ 665			$ 665