Note 4 - Goodwill and Other Intangible Assets (Details Textual) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017
Finite-lived Intangible Assets Acquired			$ 212,720
Amortization of Intangible Assets, Total	$ 13,373	$ 6,171	25,371	$ 12,115
IXYS Corporation [Member]
Finite-lived Intangible Assets Acquired			$ 212,700

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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