Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 26, 2020	Dec. 28, 2019	Dec. 29, 2018
Net sales		$ 636,007	$ 583,329	$ 451,768
Cost and expenses:
Cost of sales (1)	[1]	364,225	353,500	292,460
Research and development		86,151	86,147	56,434
Selling, general and administrative		129,248	142,936	96,754
Amortization of purchased intangible assets		38,746	39,590	17,197
Restructuring charges (Note 5)		7,623	13,484	18,704
Impairment charges		11,249	0	0
Gain on sale of facilities		(4,495)	0	0
Costs and Expenses, Total		632,747	635,657	481,549
Income (loss) from operations		3,260	(52,328)	(29,781)
Other (expense) income:
Interest expense		(13,759)	(20,556)	(4,977)
Interest income		224	764	1,187
Foreign transaction gain (loss)		(3,170)	43	1,659
Gain on extinguishment of debt		268	0	0
Loss from continuing operations before taxes		(13,177)	(72,077)	(31,912)
Income tax provision (benefit)		666	(3,082)	631
Loss from continuing operations		(13,843)	(68,995)	(32,543)
Income (loss) from discontinued operations, net of tax		42	(697)	119
Net loss		(13,801)	(69,692)	(32,424)
Net income (loss) attributable to noncontrolling interest		0	8	(243)
Net loss attributable to Cohu		$ (13,801)	$ (69,700)	$ (32,181)
Basic:
Loss from continuing operations before noncontrolling interest (in dollars per share)		$ (0.33)	$ (1.68)	$ (1.02)
Income (loss) from discontinued operations (in dollars per share)		0.00	(0.01)	0.00
Net income (loss) attributable to noncontrolling interest (in dollars per share)		0	0.00	(0.01)
Net loss attributable to Cohu (in dollars per share)		(0.33)	(1.69)	(1.01)
Diluted:
Loss from continuing operations before noncontrolling interest (in dollars per share)		(0.33)	(1.68)	(1.02)
Income (loss) from discontinued operations (in dollars per share)		0.00	(0.01)	0.00
Net income (loss) attributable to noncontrolling interest (in dollars per share)		0	0.00	(0.01)
Net loss attributable to Cohu (in dollars per share)		$ (0.33)	$ (1.69)	$ (1.01)
Weighted average shares used in computing
Basic (in shares)		41,854	41,159	31,776
Diluted (in shares)		41,854	41,159	31,776

[1] Excludes amortization of $29,510, $30,126, and $13,586 for the years ended December 26, 2020, December 28, 2019, and December 29, 2018, respectively.