Investments Non Marketable Equity (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012
Investments [Abstract]
Fair value of investment in privately held companies at acquisition	$ 8.0

This item represents the fair value of privately held companies accounted for by either the cost or equity method of accounting, as appropriate

No definition available.

Name:	mchp_CostAndEquityMethodInvestmentsInPrivateCompaniesFairValue
Namespace Prefix:	mchp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant