Net Income per Share - Schedule of Computation of Net Income per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Jun. 24, 2022	Jun. 25, 2021
Earnings Per Share [Abstract]
Net income attributable to Allegro MicroSystems, Inc.	$ 10,247	$ 27,669
Net (loss) income attributable to common stockholders, basic	10,283	27,707
Net (loss) income attributable to common stockholders, diluted	$ 10,283	$ 27,707
Basic weighted average common shares (in shares)	190,638,135	189,585,381
Dilutive effect of common stock equivalents (in shares)	1,768,141	1,577,693
Diluted weighted average common shares (in shares)	192,406,276	191,163,074
Basic net income attributable to Allegro MicroSystems, Inc. per share (in dollars per share)	$ 0.05	$ 0.15
Basic net income attributable to common stockholders per share (in dollars per share)	0.05	0.15
Diluted net income attributable to Allegro MicroSystems, Inc. per share (in dollars per share)	0.05	0.14
Diluted net income attributable to common stockholders per share (in dollars per share)	$ 0.05	$ 0.14