Net income per common share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income attributable to Microchip Technology	$ 99,402	$ 86,057	$ 93,641	$ 89,909					$ 369,009	$ 395,281	$ 127,389
Weighted average common shares outstanding									200,937,000	198,291,000	194,595,000
Dilutive effect of stock options and RSUs									3,642,000	3,910,000	3,650,000
Dilutive effect of convertible debt									18,982,440	15,429,003	7,531,111
Weighted average common and potential common shares outstanding									223,561,000	217,630,000	205,776,000
Basic net income per common share attributable to Microchip Technology stockholders									$ 1.84	$ 1.99	$ 0.65
Diluted net income per common share attributable to Microchip Technology stockholders	$ 0.45	$ 0.39	$ 0.42	$ 0.40	$ 0.50	$ 0.48	$ 0.46	$ 0.37	$ 1.65	$ 1.82	$ 0.62
Number of antidilutive option shares (in shares)									19,305	0	98,068
Junior Subordinated Convertible Debentures Due2037 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									$ 25.48	$ 26.32	$ 27.36
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									$ 68.25