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

Carrying amount as of the balance sheet date which is expected to be paid in the next twelve months.

No definition available.

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

Carrying amount as of the balance sheet date which is expected to be paid after one year.

No definition available.

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

Amount of cash paid or adjustments made in the period to fully or partially settle a specified, previously accrued cost including 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_AccruedSpecialChargesSettled
Namespace Prefix:	ment_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Percentage of termination benefit paid as of the balance sheet date.

No definition available.

Name:	ment_PercentageOfTerminationBenefitPaid
Namespace Prefix:	ment_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Amount of expenses associated with special charges including employee terminations, expenses related to certain litigation, expenses incurred related to acquisitions, excess facility costs, and other asset related charges. Excludes expenses related to a discontinued operation or an asset retirement obligation.

No definition available.

Name:	ment_SpecialCharges
Namespace Prefix:	ment_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Name:	us-gaap_RestructuringCostAndReserveAxis=ment_EarlyRetirementBenefitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RestructuringCostAndReserveAxis=us-gaap_EmployeeSeveranceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RestructuringCostAndReserveAxis=ment_LitigationCostsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: