Goodwill and Acquired Intangibles (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Apr. 04, 2015	Mar. 29, 2014
Amortization of acquired intangibles
Cost of product and maintenance	$ 10,173	$ 7,576
Amortization of acquired intangibles	6,231us-gaap_AmortizationOfIntangibleAssets	5,210us-gaap_AmortizationOfIntangibleAssets
Total amortization of acquired intangibles	$ 16,404cdns_AmortizationOfAcquiredIntangibles	$ 12,786cdns_AmortizationOfAcquiredIntangibles

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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

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-Name Accounting Standards Codification

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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