Note 2 - Business Acquisitions, Goodwill and Purchased Intangible Assets - Preliminary Allocation of Intangible Assets, Xcerra Acquisition (Details) - USD ($) $ in Thousands		3 Months Ended
	Oct. 01, 2018	Mar. 30, 2019	Dec. 29, 2018
Intangible assets, estimated fair value	$ 321,160
Gross carrying amount		$ 314,042	$ 317,857
Accumulated amortization		$ 44,995	35,203
Remaining weighted average amortization period (Year)
In-process Technology [Member]
Indefinite-lived intangible assets, estimated fair value	36,360
Developed Technology Rights [Member]
Finite-lived intangible assets, estimated fair value	$ 194,600
Finite-lived intangible assets, average useful life (Year)	7 years 292 days
Gross carrying amount		$ 212,238	214,266
Accumulated amortization		$ 27,975	21,197
Remaining weighted average amortization period (Year)		7 years 73 days
Customer Relationships [Member]
Finite-lived intangible assets, estimated fair value	$ 65,890
Finite-lived intangible assets, average useful life (Year)	10 years 219 days
Gross carrying amount		$ 72,575	73,104
Accumulated amortization		$ 9,198	7,378
Remaining weighted average amortization period (Year)		9 years 328 days
Order or Production Backlog [Member]
Finite-lived intangible assets, estimated fair value	$ 6,410
Finite-lived intangible assets, average useful life (Year)	292 days
Gross carrying amount		$ 6,342	6,372
Accumulated amortization		$ 5,433	4,696
Remaining weighted average amortization period (Year)		109 days
Trade Names [Member]
Finite-lived intangible assets, estimated fair value	$ 16,800
Finite-lived intangible assets, average useful life (Year)	11 years
Gross carrying amount		$ 22,569	22,701
Accumulated amortization		$ 2,317	1,807
Remaining weighted average amortization period (Year)		10 years 109 days
Off-Market Favorable Lease [Member]
Finite-lived intangible assets, estimated fair value	$ 1,100
Finite-lived intangible assets, average useful life (Year)	5 years 182 days
Gross carrying amount			1,100
Accumulated amortization			62
Remaining weighted average amortization period (Year)		5 years 36 days
Noncompete Agreements [Member]
Gross carrying amount		$ 318	314
Accumulated amortization		$ 72	$ 63
Remaining weighted average amortization period (Year)		7 years 292 days