Note 8 - Segment and Geographic Information - Summary of Current Segments (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 30, 2019	Mar. 31, 2018	Dec. 29, 2018
Net sales	[1]	$ 147,809	$ 95,150
Profit (loss) for reportable segments		(14,025)	12,135
Interest expense		(5,507)	(11)
Interest income		222	247
Income (loss) from continuing operations		(23,051)	10,249
Total assets for reportable segments		1,106,197		$ 1,134,002	[2]
Total assets		4,216		3,820
Corporate, Non-Segment [Member]
Corporate expenses		(3,741)	(2,122)
Total assets for reportable segments		22,541		34,367
Semiconductor Test and Inspection [Member]
Net sales		136,694	95,150
Profit (loss) for reportable segments		(15,044)	12,135
Total assets for reportable segments		1,018,515		1,038,053
PCB Test [Member]
Net sales		11,115
Profit (loss) for reportable segments		1,019
Total assets for reportable segments		60,925		57,762
Semiconductor Test and Inspection and PCB Test [Member]
Total assets for reportable segments		$ 1,079,440		$ 1,095,815

[1] After the acquisition of Xcerra on October 1, 2018 we report in two segments, Semiconductor Test & Inspection and PCB Test. Cohu's historical reported net sales would have been reported in our Semiconductor Test & Inspection segment and have been presented accordingly.

[2] Derived from December 29, 2018 audited financial statements