Acquired technology costs capitalized to the balance sheet during the period.

No definition available.

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

- Definition

The percentage of finance fees to total net revenue as of year end.

+ References

No definition available.

+ Details

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

- Details

Name:	ment_SignificantAccountingPoliciesLineItems
Namespace Prefix:	ment_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=ment_PurchasedTechnologyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_EquipmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_LandImprovementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_LeaseholdImprovementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_OtherIntangibleAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Summary of Significant Accounting Policies Significant Accounting Policies - Additional Information (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2013
Significant Accounting Policies
Finance fee percentage of revenue	2.00%ment_FinanceFeePercentageOfRevenue	2.00%ment_FinanceFeePercentageOfRevenue	2.00%ment_FinanceFeePercentageOfRevenue
Capitalized acquired technology costs		$ 3,698ment_CapitalizedAcquiredTechnologyCosts
Building
Significant Accounting Policies
Property, plant and equipment, useful life	40 years
Land Improvements
Significant Accounting Policies
Property, plant and equipment, useful life	20 years
Equipment \| Minimum
Significant Accounting Policies
Property, plant and equipment, useful life	3 years
Equipment \| Maximum
Significant Accounting Policies
Property, plant and equipment, useful life	5 years
Leasehold Improvements \| Minimum
Significant Accounting Policies
Property, plant and equipment, useful life	3 years
Leasehold Improvements \| Maximum
Significant Accounting Policies
Property, plant and equipment, useful life	10 years
Purchased Technology \| Minimum
Significant Accounting Policies
Finite-Lived intangible asset, useful life	3 years
Purchased Technology \| Maximum
Significant Accounting Policies
Finite-Lived intangible asset, useful life	5 years
Other Intangible Assets \| Minimum
Significant Accounting Policies
Finite-Lived intangible asset, useful life	2 years
Other Intangible Assets \| Maximum
Significant Accounting Policies
Finite-Lived intangible asset, useful life	5 years
Frontline
Significant Accounting Policies
Equity method investment, ownership percentage	50.00%