Goodwill and Acquired Intangibles (Details 2) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Amortization of acquired intangibles
Cost of product and maintenance	$ 11,484	$ 11,299	$ 22,344	$ 21,153
Amortization of acquired intangibles	4,590	3,159	8,796	6,467
Total amortization of acquired intangibles	$ 16,074	$ 14,458	$ 31,140	$ 27,620

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.

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