Stockholders Equity Dividend (Details) (USD $)	3 Months Ended
Apr. 30, 2013
Stockholders' Equity Attributable to Parent [Abstract]
Common Stock Dividend Per Share Annual Amount	$ 0.18

Common Stock Dividend Per Share Annual Amount Intended

No definition available.

Name:	ment_CommonStockDividendPerShareAnnualAmount
Namespace Prefix:	ment_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration