Note 4 - Goodwill and Other Intangible Assets - Amounts for Goodwill and Changes in Carrying Value by Operating Segment (Details) - USD ($) $ in Thousands			12 Months Ended
		Mar. 25, 2016	Dec. 30, 2017		Dec. 31, 2016
Balance			$ 403,544		$ 189,767
Additions			36,716	[1]	232,934	[2]
Impairments	[3]				(8,794)
Adjustments	[4]				(10,363)
Adjustments	[5]		13,154
Balance			453,414		403,544
Electronics [Member]
Balance			215,765		58,246
Additions		$ 103,800	36,716	[1]	162,172	[2]
Impairments	[3]
Adjustments	[4]				(4,653)
Adjustments	[5]		26,478
Balance			278,959		215,765
Automotive [Member]
Balance			144,585		80,262
Additions		$ 61,300		[1]	70,762	[2]
Impairments	[3]
Adjustments	[4]				(6,439)
Adjustments	[5]		(8,756)
Balance			135,829		144,585
Industrial [Member]
Balance			43,194		51,259
Additions				[1]		[2]
Impairments					(8,794)
Adjustments	[4]				729
Adjustments	[5]		(4,568)
Balance			$ 38,626		$ 43,194

[1] The 2017 additions resulted from the acquisitions of U.S. Sensor and Monolith.

[2] The 2016 additions resulted primarily from the acquisitions of PolySwitch, ON and Menber's.

[3] The 2016 impairments in the Industrial segment was due to the $8.8 million impairment of Custom Products reporting unit goodwill.

[4] Adjustments in 2016 reflect the impact of changes in foreign exchange rates.

[5] Adjustments in 2017 reflect adjustments to correct goodwill by segment as well as the impact of changes in foreign exchange rates. The impact of the corrections was an increase in goodwill to the Electronics segment of $21.6 million and a decrease of goodwill of $16.8 million and $4.8 million to the Automotive segment and the Industrial segment, respectively.