Note 2 - Business Acquisitions, Goodwill and Purchased Intangible Assets - Preliminary Allocation of Intangible Assets, Xcerra Acquisition (Details) - USD ($) $ in Thousands			9 Months Ended
		Oct. 01, 2018	Sep. 28, 2019	Dec. 29, 2018
Intangible assets, estimated fair value		$ 321,160
Gross carrying amount			$ 324,163	$ 317,857
Accumulated amortization			$ 64,544	35,203
Remaining weighted average amortization period (Year)
In-process Technology [Member]
Finite-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			$ 223,454	214,266
Accumulated amortization			$ 42,021	21,197
Remaining weighted average amortization period (Year)			6 years 292 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			$ 71,720	73,104
Accumulated amortization			$ 12,815	7,378
Remaining weighted average amortization period (Year)			9 years 182 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			$ 6,279	6,372
Accumulated amortization			$ 6,279	4,696
Remaining weighted average amortization period (Year)			0 years
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			$ 22,384	22,701
Accumulated amortization			$ 3,339	1,807
Remaining weighted average amortization period (Year)			9 years 292 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]			1,100
Accumulated amortization	[1]			62
Remaining weighted average amortization period (Year)	[1]		4 years 219 days
Noncompete Agreements [Member]
Gross carrying amount			$ 326	314
Accumulated amortization			$ 90	$ 63
Remaining weighted average amortization period (Year)			7 years 109 days

[1] Favorable leases were reclassified from intangible assets, net to operating lease right of use assets on December 30, 2018 as a result of our adoption of ASU 2016-2, Leases (Topic 842)