Net income per common share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income attributable to Microchip Technology	$ 64,899	$ 93,641	$ 195,566	$ 183,550
Weighted average common shares outstanding	204,275,000	200,629,000	203,254,000	200,408,000
Dilutive effect of stock options and RSUs	3,065,000	3,767,000	3,228,000	3,780,000
Dilutive effect of 2037 junior subordinated convertible debentures	9,759,393	20,887,608	10,451,083	20,717,720
Weighted average common and potential common shares outstanding	217,099,000	225,284,000	216,933,000	224,906,000
Basic net income per common share attributable to Microchip Technology stockholders	$ 0.32	$ 0.47	$ 0.96	$ 0.92
Diluted net income per common share attributable to Microchip Technology stockholders	$ 0.30	$ 0.42	$ 0.90	$ 0.82
Number of antidilutive option shares (in shares)	182,848	0	47,296	0
Junior Subordinated Convertible Debentures Due 2037 Member
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Weighted average conversion price per share used in calculating dilutive effect of convertible debt (amount per share)	$ 24.87	$ 25.58	$ 24.94	$ 25.67
Senior Subordinated Convertible Debenture Due 2025 [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Weighted average conversion price per share used in calculating dilutive effect of convertible debt (amount per share)	$ 67.55		$ 67.75