Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Net sales		$ 583,329	$ 451,768	$ 352,704
Cost and expenses:
Cost of sales (1)	[1]	353,500	292,460	209,297
Research and development		86,147	56,434	40,737
Selling, general and administrative		142,936	96,754	60,737
Amortization of purchased intangible assets		39,590	17,197	4,208
Restructuring charges (Note 5)		13,484	18,704
		635,657	481,549	314,979
Income (loss) from operations		(52,328)	(29,781)	37,725
Other (expense) income:
Interest expense		(20,556)	(4,977)	(54)
Interest income		764	1,187	671
Foreign transaction gain (loss) and other		43	1,659	(2,977)
Income (loss) from continuing operations before taxes		(72,077)	(31,912)	35,365
Income tax provision (benefit)		(3,082)	631	2,244
Income (loss) from continuing operations		(68,995)	(32,543)	33,121
Income (loss) from discontinued operations, net of tax		(697)	119	(278)
Net income (loss)		(69,692)	(32,424)	32,843
Net income (loss) attributable to noncontrolling interest		8	(243)
Net income (loss) attributable to Cohu		$ (69,700)	$ (32,181)	$ 32,843
Weighted average shares used in computing income (loss) per share:
Basic (in shares)		41,159	31,776	27,836
Diluted (in shares)		41,159	31,776	28,916
Basic:
Income (loss) from continuing operations before non-controlling interest (in dollars per share)		$ (1.68)	$ (1.02)	$ 1.19
Income (loss) from discontinued operations (in dollars per share)	[1]	(0.01)	0	(0.01)
Net income (loss) attributable to noncontrolling interest (in dollars per share)		0	(0.01)
Net income (loss) attributable to Cohu (in dollars per share)		(1.69)	(1.01)	1.18
Diluted:
Income (loss) from continuing operations before non-controlling interest (in dollars per share)		(1.68)	(1.02)	1.15
Income (loss) from discontinued operations (in dollars per share)	[1]	(0.01)	0	(0.01)
Net income (loss) attributable to noncontrolling interest (in dollars per share)		0	(0.01)
Net income (loss) attributable to Cohu (in dollars per share)		$ (1.69)	$ (1.01)	$ 1.14

[1] Excludes amortization of $30,126, $13,586, and $2,689 for the years ended December 28, 2019, December 29, 2018, and December 30, 2017, respectively.