Mentor Graphics (MENT) 10-Q 4 Dec 14 2015 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Oct. 31, 2014	Dec. 02, 2014
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	31-Oct-14	'
Document Fiscal Year Focus	'2015	'
Document Fiscal Period Focus	'Q3	'
Trading Symbol	'MENT	'
Entity Registrant Name	'MENTOR GRAPHICS CORP	'
Entity Central Index Key	'0000701811	'
Current Fiscal Year End Date	'--01-31	'
Entity Filer Category	'Large Accelerated Filer	'
Common Stock, Shares, Outstanding	'	115,101,672

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Income (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Revenues:	'	'	'	'
System and software	$178,115	$170,835	$475,824	$444,322
Service and support	114,568	104,807	329,243	311,051
Total revenues	292,683	275,642	805,067	755,373
Cost of revenues:	'	'	'	'
System and software	11,821	15,947	54,977	40,082
Service and support	33,670	29,396	93,684	88,380
Amortization of purchased technology	2,050	729	5,252	2,648
Total cost of revenues	47,541	46,072	153,913	131,110
Gross profit	245,142	229,570	651,154	624,263
Operating expenses:	'	'	'	'
Research and development	96,269	86,799	268,262	246,823
Marketing and selling	89,875	85,746	256,814	244,664
General and administration	19,851	18,917	57,006	52,452
Equity in earnings of Frontline	-1,184	-1,392	-4,625	-2,739
Amortization of intangible assets	2,233	1,440	6,009	4,650
Special charges	8,375	4,688	19,409	12,570
Total operating expenses	215,419	196,198	602,875	558,420
Operating income	29,723	33,372	48,279	65,843
Other income (expense), net	-381	352	-743	-879
Interest expense	-4,934	-4,967	-14,326	-14,649
Income before income tax	24,408	28,757	33,210	50,315
Income tax expense	3,849	3,634	1,907	1,864
Net income	20,559	25,123	31,303	48,451
Less: Loss attributable to noncontrolling interest	-471	-412	-1,348	-1,271
Net income attributable to Mentor Graphics shareholders	$21,030	$25,535	$32,651	$49,722
Net income per share:	'	'	'	'
Basic	$0.18	$0.21	$0.30	$0.40
Diluted	$0.18	$0.20	$0.29	$0.39
Weighted average number of shares outstanding:	'	'	'	'
Basic	114,405	113,986	114,399	113,232
Diluted	116,715	117,078	116,928	116,395
Cash dividends declared per common share	$0.05	$0.05	$0.15	$0.14

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Net income	$20,559	$25,123	$31,303	$48,451
Other comprehensive income (loss), net of tax:	'	'	'	'
Change in unrealized gain (loss) on derivative instruments	-145	211	-294	-59
Less: reclassification adjustment for net income (loss) included in net income	-165	209	-248	-58
Net change	20	2	-46	-1
Change in accumulated translation adjustment	-11,790	3,947	-12,493	-3,489
Change in pension liability	-2	-2	-6	-6
Other comprehensive income (loss)	-11,772	3,947	-12,545	-3,496
Comprehensive income	8,787	29,070	18,758	44,955
Net loss attributable to noncontrolling interest	-471	-412	-1,348	-1,271
Change in accumulated translation adjustment attributable to the noncontrolling interest	3	-46	8	2
Comprehensive loss attributable to the noncontrolling interest	-468	-458	-1,340	-1,269
Comprehensive income attributable to Mentor Graphics shareholders	$9,255	$29,528	$20,098	$46,224

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Oct. 31, 2014	Jan. 31, 2014
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$172,608	$293,322
Short-term investments	0	3,990
Trade accounts receivable, net of allowance for doubtful accounts of $3,352 as of October 31, 2014 and $5,469 as of January 31, 2014	420,407	454,483
Other receivables	16,382	15,506
Inventory	24,910	25,121
Prepaid expenses and other	22,165	24,031
Deferred income taxes	9,636	13,656
Total current assets	666,108	830,109
Property, plant, and equipment, net of accumulated depreciation of $334,713 as of October 31, 2014 and $320,827 as of January 31, 2014	155,801	160,165
Term receivables	257,028	270,365
Goodwill	598,558	549,044
Intangible assets, net of accumulated amortization of $206,287 as of October 31, 2014 and $195,752 as of January 31, 2014	48,932	22,799
Other assets	72,560	71,627
Total assets	1,798,987	1,904,109
Current liabilities:	'	'
Short-term borrowings	1,291	9,590
Accounts payable	11,526	21,548
Income taxes payable	245	3,365
Accrued payroll and related liabilities	69,974	102,848
Accrued and other liabilities	42,344	42,457
Deferred revenue	197,895	231,179
Total current liabilities	323,275	410,987
Notes payable	228,824	224,261
Deferred revenue	22,780	17,398
Income tax liability	18,173	18,431
Other long-term liabilities	32,057	32,259
Total liabilities	625,109	703,336
Commitments and contingencies	'	'
Noncontrolling interest with redemption feature	12,687	15,479
Stockholders' equity:	'	'
Common stock, no par value, 300,000 shares authorized as of October 31, 2014 and January 31, 2014; 115,055 shares issued and outstanding as of October 31, 2014 and 115,722 shares issued and outstanding as of January 31, 2014	810,375	838,939
Retained earnings	344,330	327,552
Accumulated other comprehensive income	6,250	18,803
Noncontrolling interest	236	0
Total stockholders’ equity	1,161,191	1,185,294
Total liabilities and stockholders' equity	$1,798,987	$1,904,109

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $)	Oct. 31, 2014	Jan. 31, 2014
In Thousands, except Per Share data, unless otherwise specified
Allowance for doubtful accounts receivable, current	$3,352	$5,469
Property, plant, and equipment, accumulated depreciation	334,713	320,827
Intangible assets, accumulated amortization	$206,287	$195,752
Common stock, no par value	$0	$0
Common stock, shares authorized	300,000	300,000
Common stock, shares issued	115,055	115,722
Common stock, shares outstanding	115,055	115,722

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Oct. 31, 2014	Oct. 31, 2013
Operating Cash Flows:	'	'
Net income	$31,303	$48,451
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation of property, plant, and equipment	25,683	26,104
Amortization of intangible assets, debt costs and other	17,581	13,303
Stock-based compensation	26,391	21,269
Deferred income taxes	1,208	4,121
Changes in other long-term liabilities	973	-3,405
Dividends received from unconsolidated entities, net of equity in income (loss)	-103	1,136
Other	80	-15
Changes in operating assets and liabilities, net of effect of acquired businesses:	'	'
Trade accounts receivable, net	44,977	42,210
Prepaid expenses and other	-10,533	-11,087
Term receivables, long-term	15,679	8,621
Accounts payable and accrued liabilities	-53,136	-39,787
Income taxes payable	-4,428	-6,190
Deferred revenue	-38,597	-40,705
Net cash provided by operating activities	57,078	64,026
Investing Cash Flows:	'	'
Proceeds from sales and maturities of short-term investments	4,124	3,112
Purchases of short-term investments	0	-7,820
Purchases of property, plant, and equipment	-21,872	-21,366
Acquisitions of businesses, equity interests and other intangible assets, net of cash acquired	-78,600	-6,408
Net cash used in investing activities	-96,348	-32,482
Financing Cash Flows:	'	'
Proceeds from issuance of common stock	17,409	37,801
Repurchase of common stock	-70,053	-49,995
Dividends paid	-17,168	-15,239
Net decrease in short-term borrowing	-8,243	-3,990
Repayments of other borrowings	-2,011	-2,712
Net repurchase of subsidiary shares from non-controlling interest	-121	0
Net cash used in financing activities	-80,187	-34,135
Effect of exchange rate changes on cash and cash equivalents	-1,257	-1,285
Net change in cash and cash equivalents	-120,714	-3,876
Cash and cash equivalents at the beginning of the period	293,322	223,783
Cash and cash equivalents at the end of the period	$172,608	$219,907

General

General	9 Months Ended
	Oct. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
General	'
	General
	The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with United States (U.S.) generally accepted accounting principles (GAAP) and reflect all material normal recurring adjustments. However, certain information and footnote disclosures normally included in consolidated financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). In the opinion of management, the condensed consolidated financial statements include adjustments necessary for a fair presentation of the results of the interim periods presented. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and the notes included in our Annual Report on Form 10-K for the fiscal year ended January 31, 2014.
	The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, and contingencies as of the date of the financial statements, and the reported amounts of revenues and expenses during the reporting periods. Actual results could differ from these estimates. Any changes in estimates will be reflected in the financial statements in future periods.
	The condensed consolidated financial statements include our financial statements and those of our wholly-owned and majority-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation.

Recent_Accounting_Pronouncemen

Recent Accounting Pronouncements Recent Accounting Pronouncements	9 Months Ended
	Oct. 31, 2014
Recent Accounting Pronouncements [Abstract]	'
Recent Accounting Pronouncements	'
	Recent Accounting Pronouncements
	In September 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2014-15, Presentation of Financial Statements - Going Concern: Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern. This ASU provides guidance on management's responsibility in evaluating whether there are conditions or events that raise substantial doubt about the entity's ability to continue as a going concern and to provide related disclosures if required. Evaluation is required every reporting period, including interim periods. We will be required to implement this guidance in the fourth quarter of fiscal year 2017. Early adoption is permitted. This update is not expected to have a material impact on our consolidated financial statements.
	In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). This ASU is based on the principle that the amount of revenue recognized should reflect the consideration an entity expects to be entitled to in exchange for the transfer of goods and services to customers. This ASU requires disclosures enabling users of financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. This ASU also requires qualitative and quantitative disclosure about customer contracts, significant judgments and changes in judgments, and assets recognized from the costs to obtain or fulfill a contract. We will be required to implement this guidance in the first quarter of fiscal year 2018. Early adoption is not permitted. The standard permits one of two methods for adoption: (i) retrospectively to each prior reporting period presented, with the ability to utilize certain practical expedients; or (ii) retrospectively with the cumulative effect of initially applying ASU 2014-09 recognized at the date of initial application, including additional disclosures. We are evaluating the effect that ASU 2014-09 will have on our consolidated financial statements and related disclosures. We have not yet selected a transition method, nor have we determined the effect of the standard on our ongoing financial reporting.
	In April 2014, the FASB issued ASU 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity. This ASU states that only disposals of components of an entity representing a strategic shift in operations that have or will have a major impact on operations and financial results will be presented as discontinued operations. This update requires the assets and liabilities of a discontinued operation to be presented separately in the statement of financial position for the current year and all prior periods presented. ASU 2014-08 is to be applied prospectively. We will be required to implement this guidance in the first quarter of fiscal year 2016. This update is not expected to have a material impact on our consolidated financial statements.

Fair_Value_Measurement

Fair Value Measurement	9 Months Ended
	Oct. 31, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Measurement	'
	Fair Value Measurement
	The following table presents information about financial assets and liabilities measured at fair value on a recurring basis as of October 31, 2014:
		Fair Value				Level 1		Level 2		Level 3
	Contingent consideration	$	(4,495	)		$	—	$	—	$	(4,495	)
	The following table presents information about financial assets and liabilities measured at fair value on a recurring basis as of January 31, 2014:
		Fair Value				Level 1		Level 2		Level 3
	Bank certificates of deposit	$	3,990			$	—	$	3,990	$	—
	Contingent consideration	(4,571		)		—		—		(4,571		)
	Total	$	(581	)		$	—	$	3,990	$	(4,571	)
	The FASB's authoritative guidance for the hierarchy of valuation techniques is based on whether the inputs to those valuation techniques are observable or unobservable. Observable inputs reflect market data obtained from independent sources. Unobservable inputs reflect our market assumptions. The fair value hierarchy consists of the following three levels:
	•Level 1—Quoted prices for identical instruments in active markets;
	•	Level 2—Quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-derived valuations whose significant inputs are observable; and
	•Level 3—One or more significant inputs to the valuation model are unobservable.
	We based the fair value of bank certificates of deposit included in short-term investments on quoted market prices for similar instruments in markets that are not active (Level 2).
	In connection with certain acquisitions, payment of a portion of the purchase price is contingent typically upon the acquired business’ achievement of certain revenue goals. As of October 31, 2014, of the total recorded balance, $1,538 was included in accrued and other liabilities and $2,957 was included in other long-term liabilities on our condensed consolidated balance sheet. As of January 31, 2014, of the total recorded balance, $1,565 was included in accrued and other liabilities and $3,006 was included in other long-term liabilities on our condensed consolidated balance sheet.
	We have estimated the fair value of our contingent consideration as the present value of the expected payments over the term of the arrangements. The fair value measurement of our contingent consideration as of October 31, 2014 encompasses the following significant unobservable inputs:
	Unobservable Inputs		Range
	Total estimated contingent consideration		$0	-	$5,020
	Discount rate		9.50%	-	16.00%
	Timing of cash flows (in years)		0	-	4
	Changes in the fair value of our contingent consideration are primarily driven by changes in the estimated amount and timing of payments, resulting from changes in the forecasted revenues of the acquired businesses. Significant changes in any of the inputs in isolation could result in a fluctuation in the fair value measurement of contingent consideration. Changes in fair value are recognized in special charges in our condensed consolidated statement of income in the period in which the change is identified.
	The following table summarizes contingent consideration activity:
	Balance as of January 31, 2014	$	4,571
	New contingent consideration	1,450
	Payments	(1,514		)
	Adjustments	(113		)
	Interest accretion	101
	Balance as of October 31, 2014	$	4,495
	The following table summarizes the fair value and carrying value of notes payable:
	As of	October 31, 2014				January 31, 2014
	Fair value of notes payable	$	298,411			$	306,535
	Carrying value of notes payable	$	228,824			$	224,261
	We based the fair value of notes payable on the quoted market price at the balance sheet date. The quoted market price for our notes payable is derived from observable inputs including our stock price, stock volatility, and interest rate (Level 2). Of the total carrying value of notes payable, none was classified as current on our condensed consolidated balance sheet as of October 31, 2014 and January 31, 2014.
	The carrying amounts of cash equivalents, trade accounts receivable, net, term receivables, short-term borrowings, accounts payable, and accrued liabilities approximate fair value because of the short-term nature of these instruments or because amounts have been appropriately discounted.

Business_Combinations_Business

Business Combinations Business Combinations	9 Months Ended
	Oct. 31, 2014
Business Combinations [Abstract]	'
Business Combination Disclosure [Text Block]	'
	Business Combinations
	For each business we acquire, the excess of the fair value of the consideration transferred over the fair value of the net tangible assets acquired and net tangible liabilities assumed is allocated to various identifiable intangible assets and goodwill. Identifiable intangible assets typically consist of purchased technology and customer-related intangibles, which are amortized to expense over their useful lives. Goodwill, representing the excess of the purchase consideration over the fair value of net tangible and identifiable intangible assets, is not amortized.
	Acquisitions during the nine months ended October 31, 2014
		Total Consideration		Net Tangible Assets Acquired		Identifiable Intangible Assets Acquired		Goodwill
	Berkeley Design Automation, Inc.	$	51,303	$	2,335	$	24,770	$	24,198
	Other	42,165		827		13,440		27,898
	Total	$	93,468	$	3,162	$	38,210	$	52,096
	On March 20, 2014, we acquired for cash all of the outstanding common shares of Berkeley Design Automation, Inc. (BDA), a leader in nanometer analog, mixed signal, and radio frequency circuit verification. The acquisition of BDA aligns with our goal to deliver technologies with superior performance and automation for the growing challenges of Analog/Mixed-Signal verification. The total cash consideration consisted of $46,832 paid during the nine months ended October 31, 2014 and a deferred payment valued at $4,471.
	The identified intangible assets acquired consisted of purchased technology with a fair value of $11,200 and other intangibles with a fair value of $13,570. The fair values of the identified intangible assets were valued using an income approach with significant unobservable inputs (Level 3). The significant unobservable inputs include annual revenue derived from each identified intangible asset and a selected discount rate of 15%. We are amortizing purchased technology to cost of revenues over five years and other intangibles to operating expenses over two to five years. The goodwill created by the transaction is not deductible for tax purposes. Key factors that make up the goodwill created by the transaction include expected synergies from the combination of operations and products and the knowledge and experience of the acquired workforce.
	Other acquisitions for the nine months ended October 31, 2014 consisted of three privately-held companies which were accounted for as business combinations. These acquisitions were not material individually or in the aggregate.
	The separate results of operations for the acquisitions during the nine months ended October 31, 2014 were not material, individually or in the aggregate, compared to our overall results of operations and accordingly pro forma financial statements of the combined entities have been omitted.

Term_Receivables_and_Trade_Acc

Term Receivables and Trade Accounts Receivable	9 Months Ended
	Oct. 31, 2014
Term Receivables and Trade Accounts Receivable [Abstract]	'
Term Receivables and Trade Accounts Receivable	'
	Term Receivables and Trade Accounts Receivable
	We have long-term installment receivables that are attributable to multi-year, multi-element term license sales agreements. We include balances under term agreements that are due within one year in trade accounts receivable, net and balances that are due more than one year from the balance sheet date in term receivables, long-term. We discount the total product portion of the agreements to reflect the interest component of the transaction. We amortize the interest component of the transaction, using the effective interest method, to system and software revenues over the period in which payments are made and balances are outstanding. We determine the discount rate at the outset of the arrangement based upon the current credit rating of the customer. We reset the discount rate periodically considering changes in prevailing interest rates but do not adjust previously discounted balances.
	Term receivable and trade accounts receivable balances were as follows:
	As of	October 31, 2014			January 31, 2014
	Trade accounts receivable	$	114,972		$	179,830
	Term receivables, short-term	$	305,435		$	274,653
	Term receivables, long-term	$	257,028		$	270,365
	Trade accounts receivable include billed amounts whereas term receivables, short-term are comprised of unbilled amounts. Term receivables, short-term represent the portion of long-term installment agreements that are due within one year. Billings for term agreements typically occur thirty days prior to the contractual due date, in accordance with individual contract installment terms. Term receivables, long-term represent unbilled amounts which are scheduled to be collected beyond one year.
	We perform a credit risk assessment of all customers using the Standard & Poor’s (S&P) credit rating as our primary credit-quality indicator. The S&P credit ratings are based on the most recent S&P score available at the time of assessment. For customers that do not have an S&P credit rating, we base our credit risk assessment on results provided in the customers’ most recent financial statements at the time of assessment. We determine whether or not to extend credit to these customers based on the results of our internal credit assessment, thus, mitigating our risk of loss.
	The credit risk assessment for our long-term receivables was as follows:
	As of	October 31, 2014			January 31, 2014
	S&P credit rating:
	AAA+ through BBB-	$	124,878		$	180,113
	BB+ and lower	35,051			29,654
		159,929			209,767
	Internal credit assessment	97,099			60,598
	Total long-term term receivables	$	257,028		$	270,365
	We maintain allowances for doubtful accounts on trade accounts receivable and term receivables, long-term for estimated losses resulting from the inability of our customers to make required payments. We regularly evaluate the collectibility of our trade accounts receivable based on a combination of factors. When we become aware of a specific customer’s inability to meet its financial obligations, such as in the case of bankruptcy or deterioration in the customer’s operating results, financial position, or credit rating, we record a specific reserve for bad debt to reduce the related receivable to the amount believed to be collectible. We also record unspecified reserves for bad debt for all other customers based on a variety of factors including length of time the receivables are past due, the financial health of the customers, the current business environment, and historical experience. Current economic conditions we have considered include forecasted spending in the semiconductor industry, consumer spending for electronics, integrated circuit research and development spending, and volatility in gross domestic product. If these factors change or circumstances related to specific customers change, we adjust the estimates of the recoverability of receivables resulting in either additional selling expense or a reduction in selling expense in the period the determination is made.
	We reduced our allowance for doubtful accounts during the nine months ended October 31, 2014 by $1,691, to reflect a change in estimate of our unspecified reserves resulting from sustained low write-off experience and strong collections. The adjustment was recorded in marketing and selling expense in our results of operations.
	The following shows the change in allowance for doubtful accounts:
	Allowance for doubtful accounts		Beginning balance			Expense adjustment			Other deductions(1)			Ending balance
	Nine months ended October 31, 2014		$	5,469		$	(1,865	)	$	(252	)	$	3,352
	Nine months ended October 31, 2013		$	5,331		$	(331	)	$	(93	)	$	4,907
	(1)Specific account write-offs and foreign exchange.
	We enter into agreements to sell qualifying accounts receivable from time to time to certain financing institutions on a non-recourse basis. We received net proceeds from the sale of receivables of $21,956 for the nine months ended October 31, 2014 compared to $22,267 for the nine months ended October 31, 2013. Amounts collected from customers on accounts receivable previously sold on a non-recourse basis to financial institutions are included in short-term borrowings on the balance sheet. These amounts are remitted to the financial institutions in the month following quarter-end.

ShortTerm_Borrowings

Short-Term Borrowings	9 Months Ended
	Oct. 31, 2014
Short-term Debt [Abstract]	'
Short-Term Borrowings	'
	Short-Term Borrowings
	We have a syndicated, senior, unsecured, revolving credit facility, which expires on May 24, 2017.
	The revolving credit facility has a maximum borrowing capacity of $125,000. As stated in the revolving credit facility, we have the option to pay interest based on:
	(i)	London Interbank Offered Rate (LIBOR) with varying maturities commensurate with the borrowing period we select, plus a spread of between 2.00% and 2.50% based on a pricing grid tied to a financial covenant, or
	(ii)	A base rate plus a spread of between 1.00% and 1.50%, based on a pricing grid tied to a financial covenant.
	As a result of these interest rate options, our interest expense associated with borrowings under this revolving credit facility will vary with market interest rates.
	We had no borrowings against the revolving credit facility during the nine months ended October 31, 2014 and 2013. Commitment fees are payable on the unused portion of the revolving credit facility at rates between 0.30% and 0.40% based on a pricing grid tied to a financial covenant.
	This revolving credit facility contains certain financial and other covenants, including a limit on the aggregate amount we can pay for dividends and repurchases of our stock over the term of the facility of $50,000 plus 70% of our cumulative net income for the periods after January 31, 2011.
	We were in compliance with all financial covenants as of October 31, 2014. If we fail to comply with the financial covenants and do not obtain a waiver from our lenders, we would be in default under the revolving credit facility and our lenders could terminate the facility and demand immediate repayment of all outstanding loans under the revolving credit facility.

Notes_Payable

Notes Payable	9 Months Ended
	Oct. 31, 2014
Notes Payable	'
	Notes Payable
	We have no long-term obligations maturing within the next five years. Our 4.00% Convertible Subordinated Debentures are due in 2031, but we may be required to repay them earlier under the conversion and redemption provisions described below.
	4.00% Debentures due 2031
	In April 2011, we issued $253,000 of 4.00% Convertible Subordinated Debentures (4.00% Debentures) due 2031 in a private placement pursuant to the SEC Rule 144A under the Securities Act of 1933. Interest on the 4.00% Debentures is payable semi-annually in April and October.
	As of October 31, 2014, each one thousand dollars in principal amount of the 4.00% Debentures is convertible, under certain circumstances, into 49.478 shares of our common stock (equivalent to a conversion price of $20.21 per share) for a total of 12,518 shares. The circumstances for conversion include:
	•	The market price of our common stock exceeding 120.0% of the conversion price, or $24.25 per share as of October 31, 2014, for at least 20 of the last 30 trading days in the previous fiscal quarter;
	•	A call for redemption of the 4.00% Debentures;
	•	Specified distributions to holders of our common stock;
	•	If a fundamental change, such as a change of control, occurs;
	•	During the two months prior to, but not on, the maturity date; or
	•	The market price of the 4.00% Debentures declining to less than 98% of the value of the common stock into which the 4.00% Debentures are convertible.
	Upon conversion of any 4.00% Debentures, a holder will receive:
	(i)	Cash for the lesser of the principal amount of the 4.00% Debentures that are converted or the value of the converted shares; and
	(ii)	Cash or shares of common stock, at our election, for the excess, if any, of the value of the converted shares over the principal amount.
	If a holder elects to convert their 4.00% Debentures in connection with a fundamental change in the company that occurs prior to April 5, 2016, the holder will also be entitled to receive a make whole premium upon conversion in some circumstances.
	Because we declared cash dividends during the fiscal year ended January 31, 2014 and the nine months ended October 31, 2014, the initial conversion rate for the 4.00% Debentures of 48.6902 shares of our common stock for each one thousand dollars in principal amount of the 4.00% Debentures (equivalent to a conversion price of $20.54 per share of our common stock) has been adjusted to 49.478 shares of our common stock for each one thousand dollars in principal amount of the 4.00% Debentures (equivalent to a conversion price of $20.21 per share of our common stock).
	We may redeem some or all of the 4.00% Debentures for cash on or after April 5, 2016 at the following redemption prices expressed as a percentage of principal, plus any accrued and unpaid interest:
	Period	Redemption Price
	Beginning on April 5, 2016 and ending on March 31, 2017	101.143	%
	Beginning on April 1, 2017 and ending on March 31, 2018	100.571	%
	On April 1, 2018 and thereafter	100	%
	The holders, at their option, may redeem the 4.00% Debentures for cash on April 1, 2018, April 1, 2021, and April 1, 2026, and in the event of a fundamental change in the company. In each case, our repurchase price will be 100% of the principal amount of the 4.00% Debentures plus any accrued and unpaid interest.
	The 4.00% Debentures contain a conversion feature that the debt may be settled in cash upon conversion, therefore we separately account for the implied liability and equity components of the 4.00% Debentures. The principal amount, unamortized debt discount, net carrying amount of the liability component, and carrying amount of the equity component of the 4.00% Debentures are as follows:
	As of	October 31, 2014			January 31, 2014
	Principal amount	$	253,000		$	253,000
	Unamortized debt discount	(24,176		)	(28,739		)
	Net carrying amount of the liability component	$	228,824		$	224,261
	Equity component	$	43,930		$	43,930
	The unamortized debt discount amortizes to interest expense using the effective interest method through March 2018.
	We recognized the following amounts in interest expense in the condensed consolidated statement of income related to the 4.00% Debentures:
		Three months ended October 31,						Nine months ended October 31,
		2014			2013			2014		2013
	Interest expense at the contractual interest rate	$	2,530		$	2,530		$	7,590	$	7,590
	Amortization of debt discount	$	1,548		$	1,441		$	4,563	$	4,248
	The effective interest rate on the 4.00% Debentures was 7.25% for the nine months ended October 31, 2014 and 2013.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Oct. 31, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	Commitments and Contingencies
	Indemnifications
	Our license and services agreements generally include a limited indemnification provision for claims from third parties relating to our intellectual property (IP). The indemnification is generally limited to the amount paid by the customer, a multiple of the amount paid by the customer, or a set cap. As of October 31, 2014, we were not aware of any material liabilities arising from these indemnification obligations.
	Legal Proceedings
	From time to time, we are involved in various disputes and litigation matters that arise in the ordinary course of business. These include disputes and lawsuits relating to IP rights, contracts, distributorships, and employee relations matters. Periodically, we review the status of various disputes and litigation matters and assess our potential exposure. When we consider the potential loss from any dispute or legal matter probable and the amount or the range of loss can be estimated, we will accrue a liability for the estimated loss. Legal proceedings are subject to uncertainties, and the outcomes are difficult to predict. Because of such uncertainties, we base accruals on the best information available at the time. As additional information becomes available, we reassess the potential liability related to pending claims and litigation matters and may revise estimates. We believe that the outcome of current litigation, individually and in the aggregate, will not have a material effect on our results of operations.
	In some instances, we are unable to reasonably estimate any potential loss or range of loss. The nature and progression of litigation can make it difficult to predict the impact a particular lawsuit will have. There are many reasons that we cannot make these assessments, including, among others, one or more of the following: the early stages of a proceeding; damages sought that are unspecific, unsupportable, unexplained or uncertain; discovery not having been started or incomplete; the complexity of the facts that are in dispute; the difficulty of assessing novel claims; the parties not having engaged in any meaningful settlement discussions; the possibility that other parties may share in any ultimate liability; and/or the often slow pace of litigation.
	In December 2012, Synopsys, Inc. (Synopsys) filed a lawsuit claiming patent infringement against us in federal district court in the Northern District of California, alleging that our Veloce® family of products infringes on four Synopsys U.S. patents. One of those patents is now the subject of a review by the U.S. Patent Office, and has been removed from the case pending the results of that review. The California case seeks compensatory damages relating to our emulation and field programmable gate arrays synthesis products, and is scheduled for trial in March 2015. In May 2013, Synopsys also filed a claim against us in federal district court in Oregon, similarly alleging that our Veloce family of products infringes on two additional Synopsys U.S. patents. These claims have been dismissed. We believe these actions were filed in response to patent lawsuits we filed in 2010 and 2012 against Emulation and Verification Engineering S.A. and EVE-USA, Inc. (together EVE), which Synopsys acquired in October 2012.
	On October 10, 2014, the jury in our patent lawsuit filed in the federal district court for the District of Oregon found that one of our patents - U.S. Patent No. 6,240,376 - was directly and indirectly infringed by EVE and Synopsys. As part of the verdict, the jury awarded us damages of approximately $36 million as well as certain royalties. As of October 31, 2014, nothing has been included in our financial results for this award. On November 13, 2014, we requested that the Oregon court grant a permanent injunction against future sales of Synopsys emulators. Synopsys has announced that it intends to file an appeal.
	In December 2010, we filed a patent lawsuit against EVE in Tokyo district court, which seeks compensatory damages and an injunction against the sale of EVE emulation products. The technical trial for the Japanese litigation was held in October 2014, with the court expected to deliver a verdict early in 2015.
	We do not have sufficient information upon which to determine that a loss in connection with these matters is probable, reasonably possible, or estimable, and thus no liability has been established nor has a range of loss been disclosed.

Stockholders_Equity_Notes

Stockholders Equity (Notes)	9 Months Ended
	Oct. 31, 2014
Stockholders' Equity Attributable to Parent [Abstract]	'
Stockholders' Equity Note Disclosure	'
	Stockholders' Equity
	Dividends
	On March 7, 2013, our Board of Directors announced the adoption of a dividend policy under which we commenced payment of quarterly cash dividends at an annual rate of $0.18 per share of common stock. On February 27, 2014, we announced an increase of the quarterly dividend to $0.05 per share. The following table summarizes the dividends declared:
	Declaration Date	Record Date	Payment Date	Per Share Amount		Total Amount
	3/7/13	3/22/13	4/10/13	$	0.045	$	5,064
	5/23/13	6/10/13	7/1/13	$	0.045	$	5,079
	8/22/13	9/10/13	9/30/13	$	0.045	$	5,096
	11/21/13	12/10/13	1/2/14	$	0.045	$	5,159
	2/27/14	3/10/14	3/31/14	$	0.05	$	5,778
	5/22/14	6/10/14	6/30/14	$	0.05	$	5,693
	8/21/14	9/10/14	9/30/14	$	0.05	$	5,697
	11/20/14	12/10/14	1/2/15	$	0.05
	Future declarations of quarterly dividends and the establishment of future record and payment dates are subject to the quarterly determination of our Board of Directors.

Employee_Stock_and_Savings_Pla

Employee Stock and Savings Plans	9 Months Ended
	Oct. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Employee Stock and Savings Plans	'
	Stock-Based Compensation
	Stock Option and Stock Plans
	Our 2010 Omnibus Incentive Plan (Incentive Plan) is administered by the Compensation Committee of our Board of Directors and permits accelerated vesting of outstanding options, restricted stock units, restricted stock awards, and other equity incentives upon the occurrence of certain changes in control of our company. Stock options and time-based restricted stock units under the Incentive Plan are generally expected to vest over four years. Stock options have an expiration date of ten years from the date of grant and an exercise price no less than the fair market value of the shares on the date of grant. Performance-based restricted stock units vest after three years depending on attainment of goals for operating income margin.
	Employee Stock Purchase Plans
	We have an employee stock purchase plan (ESPP) for U.S. employees and an ESPP for certain foreign subsidiary employees. The ESPPs provide for six-month offerings commencing on January 1 and July 1 of each year with purchases on June 30 and December 31 of each year. Each eligible employee may purchase up to six thousand shares of stock on each purchase date (subject to a plan limit on the total fair market value) at prices no less than 85.0% of the lesser of the fair market value of the shares on the offering date or on the purchase date.
	Stock-Based Compensation Expense
	The following table summarizes stock-based compensation expense recognized:
		Three months ended October 31,				Nine months ended October 31,
		2014		2013		2014		2013
	Cost of revenues	$	608	$	520	$	1,687	$	1,438
	Operating expenses:
	Research and development	3,651		2,865		10,203		8,018
	Marketing and selling	2,371		1,998		6,692		5,651
	General and administration	2,472		2,043		7,809		6,162
	Equity plan-related compensation expense	$	9,102	$	7,426	$	26,391	$	21,269

Incentive_Stock_Rights

Incentive Stock Rights	9 Months Ended
	Oct. 31, 2014
Incentive Stock Rights [Abstract]	'
Incentive Stock Rights	'
	Incentive Stock Rights
	Our Board of Directors has the authority to issue incentive stock in one or more series and to determine the relative rights and preferences of the incentive stock. On June 24, 2010, we adopted an Incentive Stock Purchase Rights Plan and declared a dividend distribution of one right for each outstanding share of common stock, payable to holders of record on July 6, 2010. On December 23, 2011, our Board of Directors amended the Incentive Stock Purchase Rights Plan to, among other things, extend the expiration date of the rights and increase the exercise price of each right. On June 28, 2013, our Board of Directors amended the Incentive Stock Purchase Rights Plan to extend the expiration date of the rights, change the ownership threshold for certain types of investors, increase the exercise price of each right, and add a qualifying offer provision. As long as the rights are attached to our common stock, we will issue one right with each new share of common stock so that all such shares will have attached rights. Under certain conditions, each right may be exercised to purchase 1/10,000 of a share of Series B Junior Participating Incentive Stock at a purchase price of ninety dollars, subject to adjustment. The rights are not presently exercisable and will only become exercisable if a person or group acquires or commences a tender offer to acquire 15% (20% for certain types of "passive institutional investors") or more of our common stock.
	If a person or group acquires 15% (20% for certain types of "passive institutional investors") or more of our common stock, each right will be adjusted to entitle its holder to receive, upon exercise, common stock (or, in certain circumstances, other assets of ours) having a value equal to two times the exercise price of the right, or each right will be adjusted to entitle its holder to receive, upon exercise, common stock of the acquiring company having a value equal to two times the exercise price of the right, depending on the circumstances. The rights expire on June 30, 2015 and may be redeemed by us for $0.001 per right. The rights do not have voting or dividend rights and have no dilutive effect on our earnings.

Net_Income_Loss_Per_Share

Net Income (Loss) Per Share	9 Months Ended
	Oct. 31, 2014
Earnings Per Share [Abstract]	'
Net Income (Loss) Per Share	'
	Net Income Per Share
	We compute basic net income per share using the weighted average number of common shares outstanding during the period. We compute diluted net income per share using the weighted average number of common shares and potentially dilutive common shares outstanding during the period. Potentially dilutive common shares consist of common shares issuable upon vesting of restricted stock units, exercise of stock options and ESPP purchase rights, and conversion of the 4.00% Debentures using the treasury stock method, if dilutive.
	The following provides the computation of basic and diluted net income per share:
		Three months ended October 31,						Nine months ended October 31,
		2014			2013			2014		2013
	Net income attributable to Mentor Graphics shareholders	$	21,030		$	25,535		$	32,651	$	49,722
	Noncontrolling interest adjustment to redemption value	(267		)	(2,032		)	1,295		(3,913		)
	Adjusted net income attributable to Mentor Graphics shareholders	$	20,763		$	23,503		$	33,946	$	45,809
	Weighted average common shares used to calculate basic net income per share	114,405			113,986			114,399		113,232
	Employee stock options, restricted stock units and employee stock purchase plan	2,310			3,092			2,529		3,163
	Weighted average common and potential common shares used to calculate diluted net income per share	116,715			117,078			116,928		116,395
	Net income per share attributable to Mentor Graphics shareholders:
	Basic net income per share	$	0.18		$	0.21		$	0.3	$	0.4
	Diluted net income per share	$	0.18		$	0.2		$	0.29	$	0.39
	We excluded from the computation of diluted net income per share 1,677 shares of common stock for stock options and restricted stock units for the three months ended October 31, 2014 and 1,189 shares of common stock for stock options and restricted stock units for the nine months ended October 31, 2014 compared to 73 shares of common stock for stock options for the three months ended October 31, 2013 and 1,238 shares of common stock for stock options, restricted stock units and ESPP purchase rights for the nine months ended October 31, 2013. These stock options, restricted stock units, and ESPP purchase rights were determined to be anti-dilutive as a result of applying the treasury stock method.
	We decreased the numerator of our basic and diluted earnings per share calculation by $(267) for the three months ended October 31, 2014 for the increase of the noncontrolling interest with redemption feature to its calculated redemption value, recorded directly to retained earnings. We increased the numerator of our basic and diluted earnings per share calculation by $1,295 for the nine months ended October 31, 2014 for the decrease of the noncontrolling interest with redemption feature to its calculated redemption value, recorded directly to retained earnings. We decreased the numerator of our basic and diluted earnings per share calculation by $(2,032) for the three months ended October 31, 2013 and $(3,913) for the nine months ended October 31, 2013 for the increase of the noncontrolling interest with redemption feature to its calculated redemption value, recorded directly to retained earnings.
	We assume that the 4.00% Debentures will be settled in common stock for purposes of calculating their dilutive effect. The assumed conversion of the 4.00% Debentures was anti-dilutive for all periods and therefore excluded from the computation of diluted net income per share. The conversion feature of the 4.00% Debentures, which allow for settlement in cash or a combination of cash and common stock, are further described in Note 7. “Notes Payable.”

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income	9 Months Ended
	Oct. 31, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]	'
Accumulated Other Comprehensive Income, net of tax	'
	Accumulated Other Comprehensive Income
	The following table summarizes the components of accumulated other comprehensive income, net of tax:
	As of	October 31, 2014			January 31, 2014
	Foreign currency translation adjustment	$	5,860		$	18,361
	Unrealized gain (loss) on derivatives	(4		)	42
	Pension liability	394			400
	Total accumulated other comprehensive income	$	6,250		$	18,803

Special_Charges

Special Charges	9 Months Ended
	Oct. 31, 2014
Restructuring and Related Activities [Abstract]	'
Special Charges	'
	Special Charges
	The following is a summary of the components of special charges:
		Three months ended October 31,					Nine months ended October 31,
		2014			2013		2014			2013
	Litigation costs	$	7,004		$	3,046	$	15,193		$	8,217
	Employee severance and related costs	1,377			1,133		3,077			3,843
	Other costs, net	(6		)	509		1,139			510
	Total special charges	$	8,375		$	4,688	$	19,409		$	12,570
	Special charges includes expenses incurred related to certain litigation costs, employee severance, acquisitions, excess facility costs, and asset related charges.
	Litigation costs consist of professional service fees for services rendered, related to patent litigation involving us, EVE, and Synopsys regarding emulation technology.
	Employee severance and related costs include severance benefits, notice pay, and outplacement services. These rebalance charges generally represent the aggregate of numerous unrelated rebalance plans which impact several employee groups, none of which is individually material to our financial position or results of operations. We determine termination benefit amounts based on employee status, years of service, and local statutory requirements. We communicate termination benefits to the affected employees prior to the end of the quarter in which we record the charge.
	Approximately 69% of the employee severance and related costs for the nine months ended October 31, 2014 were paid during the period. We expect to pay the remainder during the fiscal year ending January 31, 2015. Approximately 90% of the employee severance and related costs for the nine months ended October 31, 2013 were paid during the fiscal year ending January 31, 2014. There were no significant modifications to the amount of those charges.
	Accrued special charges are included in accrued and other liabilities and other long-term liabilities in the condensed consolidated balance sheets. The following table shows changes in accrued special charges during the nine months ended October 31, 2014:
		Accrued special			Charges during the nine months ended		Payments during the nine months ended			Accrued special
		charges as of								charges as of
		January 31, 2014			October 31, 2014		October 31, 2014			October 31, 2014		(1	)
	Litigation costs	$	4,855		$	15,193	$	(13,115	)	$	6,933
	Employee severance and related costs	1,004			3,077		(3,014		)	1,067
	Other costs, net	1,987			1,139		(2,218		)	908
	Total accrued special charges	$	7,846		$	19,409	$	(18,347	)	$	8,908
	(1)	Of the $8,908 total accrued special charges as of October 31, 2014, $323 represents the long-term portion, which primarily includes accrued lease termination fees and other facility costs, net of sublease income and other long-term costs. The remaining balance of $8,585 represents the short-term portion of accrued special charges.

Other_Income_Expense_Net

Other Income (Expense), Net	9 Months Ended
	Oct. 31, 2014
Other Income and Expenses [Abstract]	'
Other income (expense), net	'
	Other Income (Expense), Net
	Other income (expense), net was comprised of the following:
		Three months ended October 31,						Nine months ended October 31,
		2014			2013			2014			2013
	Interest income	$	346		$	681		$	1,290		$	1,836
	Foreign currency exchange loss	(429		)	(198		)	(1,142		)	(2,067		)
	Other, net	(298		)	(131		)	(891		)	(648		)
	Other income (expense), net	$	(381	)	$	352		$	(743	)	$	(879	)

Related_Party_Transactions

Related Party Transactions	9 Months Ended
	Oct. 31, 2014
Related Party Transactions [Abstract]	'
Related Party Transactions	'
	Related Party Transactions
	Certain members of our Board of Directors also serve as executive officers or directors for some of our customers. Management believes the transactions between these customers and us were carried out on an arm’s-length basis. We had amounts receivable from these customers of $40,119 as of October 31, 2014 and $95,789 as of January 31, 2014. The following table shows revenue recognized from these customers:
		Three months ended October 31,						Nine months ended October 31,
		2014			2013			2014			2013
	Revenues from customers	$	10,311		$	13,945		$	21,466		$	50,282
	Percentage of total revenues	3.5		%	5.1		%	2.7		%	6.7		%

Income_Taxes

Income Taxes	9 Months Ended
	Oct. 31, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes
	The provision for income taxes was comprised of the following:
		Three months ended October 31,						Nine months ended October 31,
		2014			2013			2014			2013
	Income tax expense	$	3,849		$	3,634		$	1,907		$	1,864
	Effective tax rate	15.8		%	12.6		%	5.7		%	3.7		%
	Generally, the provision for income taxes is the result of the mix of profits and losses earned in various tax jurisdictions with a broad range of income tax rates, withholding taxes (primarily in certain foreign jurisdictions), changes in tax reserves, and the application of valuation allowances on deferred tax assets. Accounting guidance for interim reporting requires that we evaluate our provision for income tax expense based on our projected results of operations for the full year and record adjustments in each quarter. Such adjustments consider period specific items and a separate determination of tax expense for entities in our consolidated group that are projected to have losses for which no tax benefit will be recognized.
	Our effective tax rate is 5.7% for the nine months ended October 31, 2014, after the inclusion of $(2,447) in net favorable period specific items. The period specific items primarily relate to reductions in liabilities for uncertain tax positions. For our full year forecast, we have projected an 11.0% effective tax rate. This rate is inclusive of period specific items recognized through October 31, 2014. Our projected rate for the full year differs from tax computed at the U.S. federal statutory rate of 35.0% primarily due to:
	•The benefit of lower tax rates on earnings of foreign subsidiaries;
	•Reduction in liabilities for uncertain tax positions; and
	•	Forecasted utilization of net operating loss carryforwards and tax credit carryforwards for which no previous benefit was recognized.
	These differences are partially offset by:
	•Repatriation of foreign subsidiary earnings to the U.S.;
	•Non-deductible equity compensation expense; and
	•Withholding taxes.
	Actual results may differ significantly from our current projections. Further, our effective tax rate could fluctuate considerably on a quarterly basis and could be significantly affected to the extent our actual mix of earnings among individual jurisdictions is different than our expectations.
	We determine deferred tax assets and liabilities based on differences between the financial reporting and tax basis of assets and liabilities. In addition, we record deferred tax assets for net operating loss carryforwards and tax credit carryforwards. We calculate the deferred tax assets and liabilities using the enacted tax rates and laws that will be in effect when we expect the differences to reverse. A valuation allowance is recorded when it is more likely than not that all or some portion of the deferred tax asset will not be realized. Since 2004, we have determined it is uncertain whether our U.S. entity will generate sufficient taxable income and foreign source income to utilize net operating loss carryforwards, research and experimentation credit carryforwards, and foreign tax credit carryforwards before expiration. Accordingly, we recorded a valuation allowance against those deferred tax assets for which realization does not meet the more likely than not standard. We have established valuation allowances related to certain foreign deferred tax assets based on historical losses as well as future expectations in certain jurisdictions. We will continue to evaluate the realizability of the deferred tax assets on a periodic basis.
	As of October 31, 2014, we had a liability of $18,418 for income taxes associated with uncertain income tax positions. Of this liability, $245 was classified as short-term liabilities in income taxes payable in our condensed consolidated balance sheet as we generally anticipate the settlement of such liabilities will require payment of cash within the next twelve months. The remaining $18,173 of income tax associated with uncertain tax positions was classified as long-term liabilities. Certain liabilities may result in the reduction of deferred tax assets rather than settlement in cash. We are not able to reasonably estimate the timing of any cash payments required to settle the long-term liabilities and do not believe that the ultimate settlement of these liabilities will materially affect our liquidity.

Supplemental_Cash_Flow_Informa

Supplemental Cash Flow Information	9 Months Ended
	Oct. 31, 2014
Supplemental Cash Flow Information [Abstract]	'
Supplemental Cash Flow Information	'
	Supplemental Cash Flow Information
	The following provides information concerning supplemental disclosures of cash flow activities:
		Nine months ended October 31,
		2014		2013
	Cash paid, net for:
	Interest	$	11,322	$	11,803
	Income taxes	$	8,836	$	7,911
	We have an investment in Frontline PCB Solutions Limited Partnership (Frontline). We received returns on investment from Frontline of $4,377 during the nine months ended October 31, 2014 and $4,000 during the nine months ended October 31, 2013, which is included in net cash provided by operating activities in our condensed consolidated statement of cash flows.

Segment_Reporting

Segment Reporting	9 Months Ended
	Oct. 31, 2014
Segment Reporting [Abstract]	'
Segment Reporting	'
	Segment Reporting
	Our Chief Operating Decision Makers (CODMs), which consist of the Chief Executive Officer and the President, review our consolidated results within one operating segment. In making operating decisions, our CODMs primarily consider consolidated financial information accompanied by disaggregated revenue information by geographic region.
	We eliminate all intercompany revenues in computing revenues by geographic regions. Revenues related to operations in the geographic regions were:
		Three months ended October 31,				Nine months ended October 31,
		2014		2013		2014		2013
	Revenues:
	United States	$	135,264	$	135,862	$	371,722	$	323,475
	Europe	64,936		57,571		180,547		151,979
	Japan	25,359		18,911		67,613		62,065
	Pacific Rim	64,346		60,341		171,022		206,783
	Other	2,778		2,957		14,163		11,071
	Total revenues	$	292,683	$	275,642	$	805,067	$	755,373
	For the three and nine months ended October 31, 2014, one customer accounted for 10.0% or more of our total revenues. For the three months ended October 31, 2013, one customer accounted for 11.0% of our total revenues. For the nine months ended October 31, 2013, no single customer accounted for 10.0% or more of our total revenues.

Fair_Value_Measurement_Policie

Fair Value Measurement (Policies)	9 Months Ended
	Oct. 31, 2014
Fair Value Disclosures [Abstract]	'
Fair value of financial instruments	'
	The FASB's authoritative guidance for the hierarchy of valuation techniques is based on whether the inputs to those valuation techniques are observable or unobservable. Observable inputs reflect market data obtained from independent sources. Unobservable inputs reflect our market assumptions. The fair value hierarchy consists of the following three levels:
	•Level 1—Quoted prices for identical instruments in active markets;
	•	Level 2—Quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-derived valuations whose significant inputs are observable; and
	•Level 3—One or more significant inputs to the valuation model are unobservable.
Short-term investments fair value determination	'
	We based the fair value of bank certificates of deposit included in short-term investments on quoted market prices for similar instruments in markets that are not active (Level 2).
Contingent consideration	'
	We have estimated the fair value of our contingent consideration as the present value of the expected payments over the term of the arrangements.
Notes payable fair value determination	'
	We based the fair value of notes payable on the quoted market price at the balance sheet date. The quoted market price for our notes payable is derived from observable inputs including our stock price, stock volatility, and interest rate (Level 2).

Term_Receivables_and_Trade_Acc1

Term Receivables and Trade Accounts Receivable (Policies)	9 Months Ended
	Oct. 31, 2014
Term Receivables and Trade Accounts Receivable [Abstract]	'
Receivables policy	'
	We include balances under term agreements that are due within one year in trade accounts receivable, net and balances that are due more than one year from the balance sheet date in term receivables, long-term. We discount the total product portion of the agreements to reflect the interest component of the transaction. We amortize the interest component of the transaction, using the effective interest method, to system and software revenues over the period in which payments are made and balances are outstanding. We determine the discount rate at the outset of the arrangement based upon the current credit rating of the customer. We reset the discount rate periodically considering changes in prevailing interest rates but do not adjust previously discounted balances.
Trade and unbilled receivables	'
	Trade accounts receivable include billed amounts whereas term receivables, short-term are comprised of unbilled amounts. Term receivables, short-term represent the portion of long-term installment agreements that are due within one year. Billings for term agreements typically occur thirty days prior to the contractual due date, in accordance with individual contract installment terms. Term receivables, long-term represent unbilled amounts which are scheduled to be collected beyond one year.
Financing receivable credit quality determination	'
	We perform a credit risk assessment of all customers using the Standard & Poor’s (S&P) credit rating as our primary credit-quality indicator. The S&P credit ratings are based on the most recent S&P score available at the time of assessment. For customers that do not have an S&P credit rating, we base our credit risk assessment on results provided in the customers’ most recent financial statements at the time of assessment. We determine whether or not to extend credit to these customers based on the results of our internal credit assessment, thus, mitigating our risk of loss.
Allowance for doubtful accounts	'
	We maintain allowances for doubtful accounts on trade accounts receivable and term receivables, long-term for estimated losses resulting from the inability of our customers to make required payments. We regularly evaluate the collectibility of our trade accounts receivable based on a combination of factors. When we become aware of a specific customer’s inability to meet its financial obligations, such as in the case of bankruptcy or deterioration in the customer’s operating results, financial position, or credit rating, we record a specific reserve for bad debt to reduce the related receivable to the amount believed to be collectible. We also record unspecified reserves for bad debt for all other customers based on a variety of factors including length of time the receivables are past due, the financial health of the customers, the current business environment, and historical experience. Current economic conditions we have considered include forecasted spending in the semiconductor industry, consumer spending for electronics, integrated circuit research and development spending, and volatility in gross domestic product. If these factors change or circumstances related to specific customers change, we adjust the estimates of the recoverability of receivables resulting in either additional selling expense or a reduction in selling expense in the period the determination is made.

Commitments_and_Contingencies_

Commitments and Contingencies (Policies)	9 Months Ended
	Oct. 31, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and contingencies policy	'
	When we consider the potential loss from any dispute or legal matter probable and the amount or the range of loss can be estimated, we will accrue a liability for the estimated loss. Legal proceedings are subject to uncertainties, and the outcomes are difficult to predict. Because of such uncertainties, we base accruals on the best information available at the time. As additional information becomes available, we reassess the potential liability related to pending claims and litigation matters and may revise estimates.

Special_Charges_Costs_Associat

Special Charges Costs Associated with Exit or Disposal Activities or Restructuring (Policies)	9 Months Ended
	Oct. 31, 2014
Restructuring and Related Activities [Abstract]	'
Costs associated with employee severance and related costs	'
	Employee severance and related costs include severance benefits, notice pay, and outplacement services. These rebalance charges generally represent the aggregate of numerous unrelated rebalance plans which impact several employee groups, none of which is individually material to our financial position or results of operations. We determine termination benefit amounts based on employee status, years of service, and local statutory requirements. We communicate termination benefits to the affected employees prior to the end of the quarter in which we record the charge.

Fair_Value_Measurement_Tables

Fair Value Measurement (Tables)	9 Months Ended
	Oct. 31, 2014
Fair Value Disclosures [Abstract]	'
Financial assets and liabilities measured at fair value on a recurring basis	'
	The following table presents information about financial assets and liabilities measured at fair value on a recurring basis as of October 31, 2014:
		Fair Value				Level 1		Level 2		Level 3
	Contingent consideration	$	(4,495	)		$	—	$	—	$	(4,495	)
	The following table presents information about financial assets and liabilities measured at fair value on a recurring basis as of January 31, 2014:
		Fair Value				Level 1		Level 2		Level 3
	Bank certificates of deposit	$	3,990			$	—	$	3,990	$	—
	Contingent consideration	(4,571		)		—		—		(4,571		)
	Total	$	(581	)		$	—	$	3,990	$	(4,571	)
Significant unobservable inputs	'
	The fair value measurement of our contingent consideration as of October 31, 2014 encompasses the following significant unobservable inputs:
	Unobservable Inputs		Range
	Total estimated contingent consideration		$0	-	$5,020
	Discount rate		9.50%	-	16.00%
	Timing of cash flows (in years)		0	-	4
Summary of level 3 activity	'
	The following table summarizes contingent consideration activity:
	Balance as of January 31, 2014	$	4,571
	New contingent consideration	1,450
	Payments	(1,514		)
	Adjustments	(113		)
	Interest accretion	101
	Balance as of October 31, 2014	$	4,495
Schedule of notes payable	'
	The following table summarizes the fair value and carrying value of notes payable:
	As of	October 31, 2014				January 31, 2014
	Fair value of notes payable	$	298,411			$	306,535
	Carrying value of notes payable	$	228,824			$	224,261

Business_Combinations_Business1

Business Combinations Business Combinations (Tables)	9 Months Ended
	Oct. 31, 2014
Business Acquisition [Line Items]	'
Schedule of Business Acquisitions, by Acquisition [Table Text Block]	'
	Acquisitions during the nine months ended October 31, 2014
		Total Consideration		Net Tangible Assets Acquired		Identifiable Intangible Assets Acquired		Goodwill
	Berkeley Design Automation, Inc.	$	51,303	$	2,335	$	24,770	$	24,198
	Other	42,165		827		13,440		27,898
	Total	$	93,468	$	3,162	$	38,210	$	52,096

Term_Receivables_and_Trade_Acc2

Term Receivables and Trade Accounts Receivable (Tables)	9 Months Ended
	Oct. 31, 2014
Term Receivables and Trade Accounts Receivable [Abstract]	'
Term receivable and trade accounts receivable balances	'
	Term receivable and trade accounts receivable balances were as follows:
	As of	October 31, 2014			January 31, 2014
	Trade accounts receivable	$	114,972		$	179,830
	Term receivables, short-term	$	305,435		$	274,653
	Term receivables, long-term	$	257,028		$	270,365
Credit risk assessment for long-term receivables	'
	The credit risk assessment for our long-term receivables was as follows:
	As of	October 31, 2014			January 31, 2014
	S&P credit rating:
	AAA+ through BBB-	$	124,878		$	180,113
	BB+ and lower	35,051			29,654
		159,929			209,767
	Internal credit assessment	97,099			60,598
	Total long-term term receivables	$	257,028		$	270,365
Change in allowance for doubtful accounts	'
	The following shows the change in allowance for doubtful accounts:
	Allowance for doubtful accounts		Beginning balance			Expense adjustment			Other deductions(1)			Ending balance
	Nine months ended October 31, 2014		$	5,469		$	(1,865	)	$	(252	)	$	3,352
	Nine months ended October 31, 2013		$	5,331		$	(331	)	$	(93	)	$	4,907
	(1)Specific account write-offs and foreign exchange.

Notes_Payable_Tables

Notes Payable (Tables)	9 Months Ended
	Oct. 31, 2014
Debt Instrument	'
Redemption prices	'
	We may redeem some or all of the 4.00% Debentures for cash on or after April 5, 2016 at the following redemption prices expressed as a percentage of principal, plus any accrued and unpaid interest:
	Period	Redemption Price
	Beginning on April 5, 2016 and ending on March 31, 2017	101.143	%
	Beginning on April 1, 2017 and ending on March 31, 2018	100.571	%
	On April 1, 2018 and thereafter	100	%
4.00% Debentures due 2031	'
Debt Instrument	'
Principal amount, unamortized debt premium (discount), net carrying amount of the liability component, and carrying amount of the equity component	'
	The principal amount, unamortized debt discount, net carrying amount of the liability component, and carrying amount of the equity component of the 4.00% Debentures are as follows:
	As of	October 31, 2014			January 31, 2014
	Principal amount	$	253,000		$	253,000
	Unamortized debt discount	(24,176		)	(28,739		)
	Net carrying amount of the liability component	$	228,824		$	224,261
	Equity component	$	43,930		$	43,930
Recognized amounts in interest expense in the condensed consolidated statement of operations related to debentures	'
	We recognized the following amounts in interest expense in the condensed consolidated statement of income related to the 4.00% Debentures:
		Three months ended October 31,						Nine months ended October 31,
		2014			2013			2014		2013
	Interest expense at the contractual interest rate	$	2,530		$	2,530		$	7,590	$	7,590
	Amortization of debt discount	$	1,548		$	1,441		$	4,563	$	4,248

Stockholders_Equity_Dividends_

Stockholders Equity Dividends Declared (Tables)	9 Months Ended
	Oct. 31, 2014
Stockholders' Equity Attributable to Parent [Abstract]	'
Dividends Declared	'
	The following table summarizes the dividends declared:
	Declaration Date	Record Date	Payment Date	Per Share Amount		Total Amount
	3/7/13	3/22/13	4/10/13	$	0.045	$	5,064
	5/23/13	6/10/13	7/1/13	$	0.045	$	5,079
	8/22/13	9/10/13	9/30/13	$	0.045	$	5,096
	11/21/13	12/10/13	1/2/14	$	0.045	$	5,159
	2/27/14	3/10/14	3/31/14	$	0.05	$	5,778
	5/22/14	6/10/14	6/30/14	$	0.05	$	5,693
	8/21/14	9/10/14	9/30/14	$	0.05	$	5,697
	11/20/14	12/10/14	1/2/15	$	0.05

Employee_Stock_and_Savings_Pla1

Employee Stock and Savings Plans (Tables)	9 Months Ended
	Oct. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Stock compensation expense recognized	'
	The following table summarizes stock-based compensation expense recognized:
		Three months ended October 31,				Nine months ended October 31,
		2014		2013		2014		2013
	Cost of revenues	$	608	$	520	$	1,687	$	1,438
	Operating expenses:
	Research and development	3,651		2,865		10,203		8,018
	Marketing and selling	2,371		1,998		6,692		5,651
	General and administration	2,472		2,043		7,809		6,162
	Equity plan-related compensation expense	$	9,102	$	7,426	$	26,391	$	21,269

Net_Income_Loss_Per_Share_Tabl

Net Income (Loss) Per Share (Tables)	9 Months Ended
	Oct. 31, 2014
Earnings Per Share [Abstract]	'
Computation of basic and diluted net income (loss) per share	'
	The following provides the computation of basic and diluted net income per share:
		Three months ended October 31,						Nine months ended October 31,
		2014			2013			2014		2013
	Net income attributable to Mentor Graphics shareholders	$	21,030		$	25,535		$	32,651	$	49,722
	Noncontrolling interest adjustment to redemption value	(267		)	(2,032		)	1,295		(3,913		)
	Adjusted net income attributable to Mentor Graphics shareholders	$	20,763		$	23,503		$	33,946	$	45,809
	Weighted average common shares used to calculate basic net income per share	114,405			113,986			114,399		113,232
	Employee stock options, restricted stock units and employee stock purchase plan	2,310			3,092			2,529		3,163
	Weighted average common and potential common shares used to calculate diluted net income per share	116,715			117,078			116,928		116,395
	Net income per share attributable to Mentor Graphics shareholders:
	Basic net income per share	$	0.18		$	0.21		$	0.3	$	0.4
	Diluted net income per share	$	0.18		$	0.2		$	0.29	$	0.39

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Tables)	9 Months Ended
	Oct. 31, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]	'
Schedule of components of accumulated other comprehensive income (loss), net of tax	'
	The following table summarizes the components of accumulated other comprehensive income, net of tax:
	As of	October 31, 2014			January 31, 2014
	Foreign currency translation adjustment	$	5,860		$	18,361
	Unrealized gain (loss) on derivatives	(4		)	42
	Pension liability	394			400
	Total accumulated other comprehensive income	$	6,250		$	18,803

Special_Charges_Summary_of_the

Special Charges Summary of the Components of Special Charges (Tables)	9 Months Ended
	Oct. 31, 2014
Restructuring and Related Activities [Abstract]	'
Schedule Of Special Charges	'
	The following is a summary of the components of special charges:
		Three months ended October 31,					Nine months ended October 31,
		2014			2013		2014		2013
	Litigation costs	$	7,004		$	3,046	$	15,193	$	8,217
	Employee severance and related costs	1,377			1,133		3,077		3,843
	Other costs, net	(6		)	509		1,139		510
	Total special charges	$	8,375		$	4,688	$	19,409	$	12,570

Special_Charges_Changes_in_Acc

Special Charges Changes in Accrued Special Charges (Tables)	9 Months Ended
	Oct. 31, 2014
Restructuring and Related Activities [Abstract]	'
Schedule Of Accrued Special Charges By Type Of Cost	'
	The following table shows changes in accrued special charges during the nine months ended October 31, 2014:
		Accrued special		Charges during the nine months ended		Payments during the nine months ended			Accrued special
		charges as of							charges as of
		January 31, 2014		October 31, 2014		October 31, 2014			October 31, 2014		(1	)
	Litigation costs	$	4,855	$	15,193	$	(13,115	)	$	6,933
	Employee severance and related costs	1,004		3,077		(3,014		)	1,067
	Other costs, net	1,987		1,139		(2,218		)	908
	Total accrued special charges	$	7,846	$	19,409	$	(18,347	)	$	8,908
	(1)	Of the $8,908 total accrued special charges as of October 31, 2014, $323 represents the long-term portion, which primarily includes accrued lease termination fees and other facility costs, net of sublease income and other long-term costs. The remaining balance of $8,585 represents the short-term portion of accrued special charges.

Other_Income_Expense_Net_Table

Other Income (Expense), Net (Tables)	9 Months Ended
	Oct. 31, 2014
Other Income and Expenses [Abstract]	'
Other income (expense), net	'
	Other income (expense), net was comprised of the following:
		Three months ended October 31,						Nine months ended October 31,
		2014			2013			2014			2013
	Interest income	$	346		$	681		$	1,290		$	1,836
	Foreign currency exchange loss	(429		)	(198		)	(1,142		)	(2,067		)
	Other, net	(298		)	(131		)	(891		)	(648		)
	Other income (expense), net	$	(381	)	$	352		$	(743	)	$	(879	)

Related_Party_Transactions_Tab

Related Party Transactions (Tables)	9 Months Ended
	Oct. 31, 2014
Related Party Transactions [Abstract]	'
Revenue recognized from related party	'
	The following table shows revenue recognized from these customers:
		Three months ended October 31,						Nine months ended October 31,
		2014			2013			2014			2013
	Revenues from customers	$	10,311		$	13,945		$	21,466		$	50,282
	Percentage of total revenues	3.5		%	5.1		%	2.7		%	6.7		%

Income_Taxes_Tables

Income Taxes (Tables)	9 Months Ended
	Oct. 31, 2014
Income Tax Disclosure [Abstract]	'
Provision for Income Taxes	'
	The provision for income taxes was comprised of the following:
		Three months ended October 31,						Nine months ended October 31,
		2014			2013			2014			2013
	Income tax expense	$	3,849		$	3,634		$	1,907		$	1,864
	Effective tax rate	15.8		%	12.6		%	5.7		%	3.7		%

Supplemental_Cash_Flow_Informa1

Supplemental Cash Flow Information (Tables)	9 Months Ended
	Oct. 31, 2014
Supplemental Cash Flow Information [Abstract]	'
Information concerning supplemental disclosures of cash flow activities	'
	The following provides information concerning supplemental disclosures of cash flow activities:
		Nine months ended October 31,
		2014		2013
	Cash paid, net for:
	Interest	$	11,322	$	11,803
	Income taxes	$	8,836	$	7,911

Segment_Reporting_Tables

Segment Reporting (Tables)	9 Months Ended
	Oct. 31, 2014
Segment Reporting [Abstract]	'
Revenues related to operations in geographic regions	'
	Revenues related to operations in the geographic regions were:
		Three months ended October 31,				Nine months ended October 31,
		2014		2013		2014		2013
	Revenues:
	United States	$	135,264	$	135,862	$	371,722	$	323,475
	Europe	64,936		57,571		180,547		151,979
	Japan	25,359		18,911		67,613		62,065
	Pacific Rim	64,346		60,341		171,022		206,783
	Other	2,778		2,957		14,163		11,071
	Total revenues	$	292,683	$	275,642	$	805,067	$	755,373

Financial_Assets_and_Liabiliti

Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) (USD $)	Oct. 31, 2014	Jan. 31, 2014
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Short-term investments	$0	$3,990
Fair Value, Measurements, Recurring	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Short-term investments	'	3,990
Contingent consideration	4,495	4,571
Fair Value, Net Asset (Liability)	'	-581
Level 1 | Fair Value, Measurements, Recurring	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Short-term investments	'	0
Contingent consideration	0	0
Fair Value, Net Asset (Liability)	'	0
Level 2 | Fair Value, Measurements, Recurring	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Short-term investments	'	3,990
Contingent consideration	0	0
Fair Value, Net Asset (Liability)	'	3,990
Level 3 | Fair Value, Measurements, Recurring	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Short-term investments	'	0
Contingent consideration	4,495	4,571
Fair Value, Net Asset (Liability)	'	($4,571)

Fair_Value_Measurement_Level_3

Fair Value Measurement Level 3 Unobservable Inputs (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Oct. 31, 2014
Unobservable Inputs [Abstract]	'
Total estimated contingent consideration, low	$0
Total estimated contingent consideration, high	$5,020
Discount rate, low	9.50%
Discount rate, high	16.00%
Timing of cash flows (in years), low	0
Timing of cash flows (in years), high	4

Summary_of_Level_3_Activity_De

Summary of Level 3 Activity (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Oct. 31, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'
Balance at beginning of period	$4,571
New contingent consideration	1,450
Payments	-1,514
Adjustment	-113
Interest accretion	101
Balance at ending of period	$4,495

Fair_Value_Measurement_Additio

Fair Value Measurement - Additional Information (Detail) (USD $)	Oct. 31, 2014	Jan. 31, 2014
In Thousands, unless otherwise specified
Fair Value Disclosures [Abstract]	'	'
Fair value of contingent consideration included in accrued liabilities	$1,538	$1,565
Fair value of contingent consideration included in other long term liabilities	2,957	3,006
Fair value of notes payable	298,411	306,535
Notes payable	228,824	224,261
Current portion of notes payable	$0	$0

Business_Combinations_Business2

Business Combinations Business Combinations (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Oct. 31, 2014	Jan. 31, 2014
Business Acquisition [Line Items]	'	'
Business Acquisition, Effective Date of Acquisition	20-Mar-14	'
Goodwill	$598,558	$549,044
Developed Technology Rights [Member]	'	'
Business Acquisition [Line Items]	'	'
Finite-Lived Intangible Asset, Useful Life	'5 years	'
Business Combination, Recognized Identifiable Finite-Lived Intangibles	11,200	'
Other Intangible Assets [Member]	'	'
Business Acquisition [Line Items]	'	'
Business Combination, Recognized Identifiable Finite-Lived Intangibles	13,570	'
Berkeley Design Automation, Inc.	'	'
Business Acquisition [Line Items]	'	'
Fair Value Inputs, Discount Rate	15.00%	'
Berkeley Design Automation, Inc.	'	'
Business Acquisition [Line Items]	'	'
Payments to Acquire Businesses, Gross	46,832	'
Acquisition Related Deferred Payment	4,471	'
Business Combination, Consideration Transferred	51,303	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	2,335	'
Business Combination, Recognized Identifiable Finite-Lived Intangibles	24,770	'
Goodwill	24,198	'
Other Acquired Entities [Member]	'	'
Business Acquisition [Line Items]	'	'
Business Combination, Consideration Transferred	42,165	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	827	'
Business Combination, Recognized Identifiable Finite-Lived Intangibles	13,440	'
Goodwill	27,898	'
Total FY15 Acquisitions [Member]	'	'
Business Acquisition [Line Items]	'	'
Business Combination, Consideration Transferred	93,468	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	3,162	'
Business Combination, Recognized Identifiable Finite-Lived Intangibles	38,210	'
Goodwill	$52,096	'
Maximum | Other Intangible Assets [Member]	'	'
Business Acquisition [Line Items]	'	'
Finite-Lived Intangible Asset, Useful Life	'5 years	'
Minimum | Other Intangible Assets [Member]	'	'
Business Acquisition [Line Items]	'	'
Finite-Lived Intangible Asset, Useful Life	'2 years	'

Term_Receivable_and_Trade_Acco

Term Receivable and Trade Accounts Receivable Balances (Detail) (USD $)	Oct. 31, 2014	Jan. 31, 2014
In Thousands, unless otherwise specified
Accounts and Financing Receivable [Line Items]	'	'
Trade accounts receivable, net	$420,407	$454,483
Term receivables, long-term	257,028	270,365
Trade accounts receivable	'	'
Accounts and Financing Receivable [Line Items]	'	'
Trade accounts receivable, net	114,972	179,830
Term receivables, short-term	'	'
Accounts and Financing Receivable [Line Items]	'	'
Trade accounts receivable, net	$305,435	$274,653

Credit_Risk_Assessment_for_Lon

Credit Risk Assessment for Long-term Receivables (Detail) (USD $)	Oct. 31, 2014	Jan. 31, 2014
In Thousands, unless otherwise specified
Accounts and Financing Receivable [Line Items]	'	'
Term receivables, long-term	$257,028	$270,365
S&P credit rating, AAA+ through BBB-	'	'
Accounts and Financing Receivable [Line Items]	'	'
Term receivables, long-term	124,878	180,113
S&P credit rating, BB+ and lower	'	'
Accounts and Financing Receivable [Line Items]	'	'
Term receivables, long-term	35,051	29,654
S&P credit rating	'	'
Accounts and Financing Receivable [Line Items]	'	'
Term receivables, long-term	159,929	209,767
Internal Credit Rating	'	'
Accounts and Financing Receivable [Line Items]	'	'
Term receivables, long-term	$97,099	$60,598

Change_in_Allowance_for_Doubtf

Change in Allowance for Doubtful Accounts (Detail) (USD $)	Oct. 31, 2014	Jan. 31, 2014	Oct. 31, 2014	Oct. 31, 2013
In Thousands, unless otherwise specified			Allowance for Doubtful Accounts [Member]	Allowance for Doubtful Accounts [Member]
Allowance for doubtful accounts receivable, beginning balance	$3,352	$5,469	$5,469	$5,331
Valuation Allowances and Reserves, Charged to Cost and Expense	'	'	-1,865	-331
Net Deductions Recoveries	'	'	-252	-93
Allowance for doubtful accounts receivable, ending balance	$3,352	$5,469	$3,352	$4,907

Term_Receivables_and_Trade_Acc3

Term Receivables and Trade Accounts Receivable - Additional Information (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Oct. 31, 2014	Oct. 31, 2013
Disclosure Term Receivables And Trade Accounts Receivable Additional Information [Abstract]	'	'
Billing period	'30 days	'
Net proceeds from sale of receivables	$21,956	$22,267
Allowance for doubtful accounts adjustment	'	'
Statement	'	'
Valuation Allowances and Reserves, Charged to Cost and Expense	$1,691	'

ShortTerm_Borrowings_Additiona

Short-Term Borrowings - Additional Information (Detail) (Revolving credit facility, USD $)	9 Months Ended
In Thousands, unless otherwise specified	Oct. 31, 2014
Line of Credit Facility [Line Items]	'
Termination date for senior, unsecured revolving credit facility	24-May-17
Revolving credit facility, maximum borrowing capacity	$125,000
Credit facility limits, aggregate amount available for dividend and repurchase of stock	$50,000
Credit facility limits, aggregate amount available for dividend and repurchase of stock, percentage of cumulative net income	70.00%
Minimum	'
Line of Credit Facility [Line Items]	'
Commitment fee percentage on unused line of credit	0.30%
Minimum | LIBOR	'
Line of Credit Facility [Line Items]	'
Basis spread	2.00%
Minimum | Base rate	'
Line of Credit Facility [Line Items]	'
Basis spread	1.00%
Maximum	'
Line of Credit Facility [Line Items]	'
Commitment fee percentage on unused line of credit	0.40%
Maximum | LIBOR	'
Line of Credit Facility [Line Items]	'
Basis spread	2.50%
Maximum | Base rate	'
Line of Credit Facility [Line Items]	'
Basis spread	1.50%

Notes_Payable_Redemption_Price

Notes Payable - Redemption Prices Expressed as a Percentage of Principal, Plus any Accrued and Unpaid Interest (Detail) (4.00% Debentures due 2031, Convertible Subordinated Debt)	9 Months Ended
	Oct. 31, 2014
Redemption period beginning on April 5, 2016 and ending on March 31, 2017	'
Debt Instrument	'
Debentures redemption price	101.14%
Redemption period beginning on April 1, 2017 and ending on March 31, 2018	'
Debt Instrument	'
Debentures redemption price	100.57%
Redemption period beginning on April 1, 2018 and thereafter	'
Debt Instrument	'
Debentures redemption price	100.00%

Notes_Payable_Principal_Amount

Notes Payable - Principal Amount, Unamortized Debt Discount, Net Carrying Amount of the Liability Component, and Carrying Amount of the Equity Component of the 4.00% Debentures (Detail) (4.00% Debentures due 2031, USD $)	Oct. 31, 2014	Jan. 31, 2014
In Thousands, unless otherwise specified
4.00% Debentures due 2031	'	'
Debt Instrument	'	'
Principal amount	$253,000	$253,000
Unamortized debt discount	-24,176	-28,739
Net carrying amount of the liability component	228,824	224,261
Equity component	$43,930	$43,930

Notes_Payable_Recognized_Amoun

Notes Payable - Recognized Amounts in Interest Expense in the Condensed Consolidated Statements of Income Related to the 4.00% Debentures (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Debt Instrument	'	'	'	'
Interest expense at the contractual interest rate	$4,934	$4,967	$14,326	$14,649
4.00% Debentures due 2031	'	'	'	'
Debt Instrument	'	'	'	'
Interest expense at the contractual interest rate	2,530	2,530	7,590	7,590
Amortization of debt discount	$1,548	$1,441	$4,563	$4,248

Notes_Payable_Additional_Infor

Notes Payable - Additional Information (Detail) (USD $)	9 Months Ended
In Thousands, except Share data, unless otherwise specified	Oct. 31, 2014	Oct. 31, 2013	Apr. 30, 2011
Debt Instrument	'	'	'
LongTermDebtMaturitiesRepaymentsOfPrincipalInNextFiveYears	$0	'	'
4.00% Debentures due 2031 | Convertible Subordinated Debt	'	'	'
Debt Instrument	'	'	'
Issued debt	'	'	253,000
Interest rate	'	'	4.00%
Conversion rate	49.478	'	48.6902
Principal amount multiple	$1	'	$1
Conversion price	$20.21	'	$20.54
Total number of shares	12,518,000	'	'
Market price of common stock exceeding percent of the conversion price	120.00%	'	'
Debt instrument conversion circumstance stock price	$24.25	'	'
Debt instrument threshold trading days	20	'	'
Debt instrument threshold consecutive trading days	'30 days	'	'
Market price of debentures declining to maximum percent of the value of the common stock	98.00%	'	'
Amortization end date	'2018-03	'	'
Debt Instrument, Interest Rate During Period	7.25%	7.25%	'
Holder optional redemption on April 1, 2018 | 4.00% Debentures due 2031 | Convertible Subordinated Debt	'	'	'
Debt Instrument	'	'	'
Debentures redemption price	100.00%	'	'
Holder optional redemption on April 1, 2021 | 4.00% Debentures due 2031 | Convertible Subordinated Debt	'	'	'
Debt Instrument	'	'	'
Debentures redemption price	100.00%	'	'
Holder optional redemption on April 1, 2026 | 4.00% Debentures due 2031 | Convertible Subordinated Debt	'	'	'
Debt Instrument	'	'	'
Debentures redemption price	100.00%	'	'

Stockholders_Equity_Dividend_D

Stockholders Equity Dividend (Details) (USD $)	3 Months Ended							9 Months Ended		0 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Oct. 31, 2014	Oct. 31, 2013	Nov. 20, 2014
										Subsequent Event [Member]
Stockholders' Equity Attributable to Parent [Abstract]	'	'	'	'	'	'	'	'	'	'
Common Stock Dividend Per Share Annual Amount	'	'	'	'	'	'	$0.18	'	'	'
Dividends Payable [Line Items]	'	'	'	'	'	'	'	'	'	'
Dividends Payable, Date Declared	21-Aug-14	22-May-14	27-Feb-14	21-Nov-13	22-Aug-13	23-May-13	7-Mar-13	'	'	20-Nov-14
Dividends Payable, Date of Record	10-Sep-14	10-Jun-14	10-Mar-14	10-Dec-13	10-Sep-13	10-Jun-13	22-Mar-13	'	'	10-Dec-14
Dividends Payable, Date to be Paid	30-Sep-14	30-Jun-14	31-Mar-14	2-Jan-14	30-Sep-13	1-Jul-13	10-Apr-13	'	'	2-Jan-15
Cash dividends declared per common share	$0.05	$0.05	$0.05	$0.05	$0.05	$0.05	$0.05	$0.15	$0.14	$0.05
Payments of Dividends	$5,697	$5,693	$5,778	$5,159	$5,096	$5,079	$5,064	$17,168	$15,239	'

StockBased_Compensation_Stock_

Stock-Based Compensation Stock Based Compensation Details Textual (Details)	9 Months Ended
In Thousands, unless otherwise specified	Oct. 31, 2014
Omnibus Incentive Plan [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period	'4 years
Share Based Compensation Arrangement By Share Based Payment Award Expiry Period From Date Of Grant	'10 years
Employee Stock Purchase Plans [Member]	'
Employee Stock Purchase Plan Maximum Number Of Shares That May Be Purchased By Eligible Participants	6
Share Based Compensation Arrangement By Share Based Payment Award Discounted Price From Market Price Offering	85.00%

StockBased_Compensation_Stock_1

Stock-Based Compensation Stock Compensation Expense (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'	'
Share-based Compensation	$9,102	$7,426	$26,391	$21,269
Cost of Sales [Member]	'	'	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'	'
Share-based Compensation	608	520	1,687	1,438
Research and Development Expense [Member]	'	'	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'	'
Share-based Compensation	3,651	2,865	10,203	8,018
Selling and Marketing Expense [Member]	'	'	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'	'
Share-based Compensation	2,371	1,998	6,692	5,651
General and Administrative Expense [Member]	'	'	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'	'
Share-based Compensation	$2,472	$2,043	$7,809	$6,162

Incentive_Stock_Rights_Additio

Incentive Stock Rights - Additional Information (Detail) (USD $)	3 Months Ended			9 Months Ended
	Oct. 31, 2013	Jan. 31, 2012	Jul. 31, 2010	Oct. 31, 2014	Jun. 24, 2010
Disclosure Incentive Stock Rights Additional Information [Abstract]	'	'	'	'	'
Dividend distribution of rights declared for each outstanding share of common stock	'	'	'	'	1
Number of shares called by rights	'	'	'	'	0.0001
Incentive stock purchase right adoption date	'	'	24-Jun-10	'	'
Incentive stock rights dividend date of record	'	'	6-Jul-10	'	'
Incentive stock purchase right amendment date	28-Jun-13	23-Dec-11	'	'	'
Right issuable with each new share of common stock	'	'	'	1	'
Incentive stock purchase price	'	'	'	$90	'
Percentage of common stock acquired to initiate exercise of incentive stock rights, minimum	'	'	'	15.00%	'
Percentage of common stock acquired to initiate exercise of incentive stock rights, certain investors	'	'	'	20.00%	'
Percent of incentive stock right exercise price for value of the entity's common stock received upon exercise of incentive stock right	'	'	'	200.00%	'
Date on which rights expire	'	'	'	30-Jun-15	'
Rights redemption price	'	'	'	$0.00	'

Net_Income_Loss_Per_Share_Comp

Net Income (Loss) Per Share - Computation of Basic and Diluted Net Income (Loss) Per Share (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Earnings Per Share Disclosure [Line Items]	'	'	'	'
Antidilutive securities excluded from computation of earnings per share, amount	1,677	73	1,189	1,238
Net income attributable to Mentor Graphics shareholders	$21,030	$25,535	$32,651	$49,722
Non-controlling interest adjustment to redemption value	-267	-2,032	1,295	-3,913
Net income (loss) attributable to Mentor Graphics shareholders, diluted	$20,763	$23,503	$33,946	$45,809
Weighted average common shares used to calculate basic net income (loss) per share (in shares)	114,405	113,986	114,399	113,232
Employee stock options, restricted stock units and employee stock purchase plan (in shares)	2,310	3,092	2,529	3,163
Weighted average common and potential common shares used to calculate diluted net income (loss) per share (in shares)	116,715	117,078	116,928	116,395
Basic net income (loss) per share attributable to Mentor Graphics shareholders (in dollars per share)	$0.18	$0.21	$0.30	$0.40
Diluted net income (loss) per share attributable to Mentor Graphics shareholders (in dollars per share)	$0.18	$0.20	$0.29	$0.39

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Income Accumulated Other Comprehensive Income (Details) (USD $)	Oct. 31, 2014	Jan. 31, 2014
In Thousands, unless otherwise specified
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'
Foreign currency translation adjustment	$5,860	$18,361
Unrealized gain (loss) on derivatives, net of tax	-4	42
Pension liability, net of tax	394	400
Accumulated other comprehensive income, net of tax	$6,250	$18,803

Summary_of_the_Components_of_t

Summary of the Components of the Special Charges (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Disclosure Summary Of Components Of Special Charges [Abstract]	'	'	'	'
Litigation costs	$7,004	$3,046	$15,193	$8,217
Employee severance and related costs	1,377	1,133	3,077	3,843
Other costs	-6	509	1,139	510
Special charges	$8,375	$4,688	$19,409	$12,570

Changes_in_Accrued_Special_Cha

Changes in Accrued Special Charges (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013	Jan. 31, 2014
Accrued special charges [Roll Forward]	'	'	'	'	'
Special charges	$8,375	$4,688	$19,409	$12,570	'
Adjustments (payments)	'	'	-18,347	'	'
Accrued Special Charges	8,908	'	8,908	'	7,846
Litigation costs	'	'	'	'	'
Accrued special charges [Roll Forward]	'	'	'	'	'
Special charges	'	'	15,193	'	'
Adjustments (payments)	'	'	-13,115	'	'
Accrued Special Charges	6,933	'	6,933	'	4,855
Employee severance and related costs	'	'	'	'	'
Accrued special charges [Roll Forward]	'	'	'	'	'
Special charges	'	'	3,077	'	'
Adjustments (payments)	'	'	-3,014	'	'
Accrued Special Charges	1,067	'	1,067	'	1,004
Other costs	'	'	'	'	'
Accrued special charges [Roll Forward]	'	'	'	'	'
Special charges	'	'	1,139	'	'
Adjustments (payments)	'	'	-2,218	'	'
Accrued Special Charges	$908	'	$908	'	$1,987

Special_Charges_Additional_Inf

Special Charges - Additional Information (Detail) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	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	'	'

Other_Income_Expense_Net_Detai

Other Income (Expense), Net (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Component of Other Expense, Nonoperating [Line Items]	'	'	'	'
Interest income	$346	$681	$1,290	$1,836
Foreign currency exchange loss	-429	-198	-1,142	-2,067
Other, net	-298	-131	-891	-648
Other income (expense), net	($381)	$352	($743)	($879)

Revenue_Recognized_from_Relate

Revenue Recognized from Related Party (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Related Party Transaction [Line Items]	'	'	'	'
Revenue from related party	$10,311	$13,945	$21,466	$50,282
Percentage of related party revenue	3.50%	5.10%	2.70%	6.70%

Related_Party_Transactions_Rel

Related Party Transactions Related Party Transactions - Additional Information (Details) (USD $)	Oct. 31, 2014	Jan. 31, 2014
In Thousands, unless otherwise specified
Related Party Transaction [Line Items]	'	'
Accounts receivable due from related party	$40,119	$95,789

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013	Jan. 31, 2014
Disclosure Income Taxes Additional Information [Abstract]	'	'	'	'	'
Income tax expense	$3,849	$3,634	$1,907	$1,864	'
Effective tax rate	15.80%	12.60%	5.70%	3.70%	'
Period specific items benefit	'	'	-2,447	'	'
Effective income tax rate forecast	'	'	11.00%	'	'
U.S. federal statutory rate	'	'	35.00%	'	'
Income taxes associated with uncertain income tax positions	18,418	'	18,418	'	'
Liability for uncertain tax positions, current	245	'	245	'	'
Income tax liability	$18,173	'	$18,173	'	$18,431

Supplemental_Cash_Flow_Informa2

Supplemental Cash Flow Information - Additional Information (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Oct. 31, 2014	Oct. 31, 2013
Schedule of Supplemental Cash Flow [Line Items]	'	'
Interest	$11,322	$11,803
Income taxes	8,836	7,911
Frontline	'	'
Schedule of Supplemental Cash Flow [Line Items]	'	'
Returns received on investment	$4,377	$4,000

Segment_Reporting_Operating_Se

Segment Reporting Operating Segment (Details)	9 Months Ended
	Oct. 31, 2014
Segment Reporting [Abstract]	'
Number of operating segments	1

Segment_Reporting_Additional_I

Segment Reporting - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Concentration Risk [Line Items]	'	'	'	'
Customers accounting for ten percent or more of net revenue	1	1	1	0
Customer concentration risk | Sales Revenue, Net [Member]	'	'	'	'
Concentration Risk [Line Items]	'	'	'	'
Customer percent of total revenues	10.00%	11.00%	10.00%	10.00%

Segment_Reporting_Revenues_Rel

Segment Reporting Revenues Related to Operations in Geographic Regions (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Revenues:	'	'	'	'
Total revenues	$292,683	$275,642	$805,067	$755,373
UNITED STATES	'	'	'	'
Revenues:	'	'	'	'
Total revenues	135,264	135,862	371,722	323,475
Europe	'	'	'	'
Revenues:	'	'	'	'
Total revenues	64,936	57,571	180,547	151,979
Japan	'	'	'	'
Revenues:	'	'	'	'
Total revenues	25,359	18,911	67,613	62,065
Asia	'	'	'	'
Revenues:	'	'	'	'
Total revenues	64,346	60,341	171,022	206,783
Americas [Member]	'	'	'	'
Revenues:	'	'	'	'
Total revenues	$2,778	$2,957	$14,163	$11,071