Net Income per Share - Schedule of Computation of Net Income per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 23, 2022	Sep. 24, 2021	Sep. 23, 2022	Sep. 24, 2021
Earnings Per Share [Abstract]
Net income attributable to Allegro MicroSystems, Inc.	$ 50,614	$ 33,186	$ 60,861	$ 60,855
Net income attributable to common stockholders, basic	50,648	33,223	60,931	60,930
Net income attributable to common stockholders, diluted	$ 50,648	$ 33,223	$ 60,931	$ 60,930
Basic weighted average shares of common stock (in shares)	191,284,631	189,673,788	190,959,616	189,629,535
Dilutive effect of common stock equivalents (in shares)	1,354,945	2,002,634	1,694,481	1,786,715
Diluted weighted average common shares (in shares)	192,639,576	191,676,422	192,654,097	191,416,250
Basic net income attributable to Allegro MicroSystems, Inc. per share (in dollars per share)	$ 0.26	$ 0.17	$ 0.32	$ 0.32
Basic net income attributable to common stockholders per share (in dollars per share)	0.26	0.18	0.32	0.32
Diluted net income attributable to Allegro MicroSystems, Inc. per share (in dollars per share)	0.26	0.17	0.32	0.32
Diluted net income attributable to common stockholders per share (in dollars per share)	$ 0.26	$ 0.17	$ 0.32	$ 0.32