Future cash outflow associated with the acquisition of business during the period.

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Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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Amount recognized as of the acquisition date for the identifiable assets acquired in excess of (less than) the aggregate liabilities assumed.

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Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

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

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

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Business Combinations (Details) - USD ($) $ in Thousands	12 Months Ended
Business Combinations (Details) - USD ($) $ in Thousands	Jan. 31, 2015	Jan. 31, 2016	Jan. 31, 2014
Business Acquisition [Line Items]
Goodwill	$ 599,929	$ 606,842	$ 549,044
Berkeley Design Automation, Inc. [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Mar. 20, 2014
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
Fair Value Inputs, Discount Rate	15.00%
Goodwill	$ 24,198
Other Acquired Entities [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	49,315
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	876
Business Combination, Recognized Identifiable Finite-Lived Intangibles	15,160
Goodwill	33,279
Total FY15 Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	100,618
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	3,211
Business Combination, Recognized Identifiable Finite-Lived Intangibles	39,930
Goodwill	57,477
Other Intangible Assets \| Berkeley Design Automation, Inc. [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Finite-Lived Intangibles	$ 13,570
Other Intangible Assets \| Minimum \| Berkeley Design Automation, Inc. [Member]
Business Acquisition [Line Items]
Finite-Lived intangible asset, useful life	2 years
Other Intangible Assets \| Maximum \| Berkeley Design Automation, Inc. [Member]
Business Acquisition [Line Items]
Finite-Lived intangible asset, useful life	5 years
Developed Technology Rights [Member] \| Berkeley Design Automation, Inc. [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Finite-Lived Intangibles	$ 11,200
Finite-Lived intangible asset, useful life	5 years