Note 2 - Business Acquisitions, Goodwill and Purchased Intangible Assets - Preliminary Allocation of Intangible Assets, Xcerra Acquisition (Details) - USD ($) $ in Thousands		6 Months Ended
	Oct. 01, 2018	Jun. 29, 2019	Dec. 29, 2018
Intangible assets, estimated fair value	$ 321,160
Gross carrying amount		$ 319,319	$ 317,857
Accumulated amortization		$ 55,645	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		$ 216,620	214,266
Accumulated amortization		$ 35,347	21,197
Remaining weighted average amortization period (Year)		6 years 328 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		$ 73,226	73,104
Accumulated amortization		$ 11,202	7,378
Remaining weighted average amortization period (Year)		9 years 255 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		$ 6,371	6,372
Accumulated amortization		$ 6,142	4,696
Remaining weighted average amortization period (Year)		36 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		$ 22,775	22,701
Accumulated amortization		$ 2,872	1,807
Remaining weighted average amortization period (Year)		10 years
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)		4 years 328 days
Noncompete Agreements [Member]
Gross carrying amount		$ 327	314
Accumulated amortization		$ 82	$ 63
Remaining weighted average amortization period (Year)		7 years 182 days