Special Charges - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
Oct. 31, 2014	Jan. 31, 2013	Jan. 31, 2014
Disclosure Special Charges Additional Information [Abstract]
Accrued Special Charges	$ 8,908		$ 7,846
Accrued Special Charges Noncurrent	323
Percentage of termination benefit paid during the period	69.00%	90.00%
Accrued Special Charges Current	$ 8,585

Carrying amount (including both current and noncurrent portions of the accrual) as of the balance sheet date pertaining to a specified type of cost associated with employee terminations, expenses related to certain litigation, expenses incurred related to acquisitions, excess facility costs, and other asset related charges.

No definition available.

Name:	ment_AccruedSpecialCharges
Namespace Prefix:	ment_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant