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				27,330			27,316
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest	27,330
Net loss attributable to noncontrolling interest						(14)	14
Unrealized gain on investments	57				57		57
Foreign currency translation	(20)				(20)		(20)
Stock options exercised	67		67				67
Stock options exercised (in shares)		6,000
Restricted stock awards (in shares)		33,412
Restricted stock awards forfeited (in shares)		(13,453)
Tax withholding payment related to net share settlement of equity awards	(819)		(819)				(819)
Tax withholding payment related to net share settlement of equity awards (in shares)		(11,353)
Stock-based compensation	1,402		1,402				1,402
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, Ending Balance at Jul. 28, 2018							437,059
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				17,110			17,099
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest	17,110
Net loss attributable to noncontrolling interest						(11)	11
Foreign currency translation	169				169		169
Stock options exercised	93		93				93
Stock options exercised (in shares)		3,000
Restricted stock awards (in shares)		57,861
Restricted stock awards forfeited (in shares)		(4,720)
Tax withholding payment related to net share settlement of equity awards	(668)		(668)				(668)
Tax withholding payment related to net share settlement of equity awards (in shares)		(11,975)
Stock-based compensation	1,566		1,566				1,566
Balance at Jul. 27, 2019	481,506	$ 2	$ 177,207	304,126	$ 171	$ (7)	481,506
Balance (in shares) at Jul. 27, 2019		23,990,459
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Jul. 27, 2019							481,499
Increase (Decrease) in Stockholders' Equity
Adoption of ASU	$ 665			$ 665			$ 665