Note 15 - Selected Quarterly Financial Data (Unaudited) - Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2016	[1]	Oct. 01, 2016	[2]	Jul. 02, 2016	[3]	Apr. 02, 2016	[4]	Jan. 02, 2016	[5]	Sep. 26, 2015	[6]	Jun. 27, 2015	[7]	Mar. 28, 2015	[8]	Dec. 31, 2016	Jan. 02, 2016	Dec. 27, 2014
Net sales	$ 284,518		$ 280,331		$ 271,912		$ 219,398		$ 220,020		$ 215,510		$ 222,021		$ 210,313		$ 1,056,159	$ 867,864	$ 851,995
Gross profit	114,337		113,759		97,866		87,155		82,706		86,182		85,281		76,330		413,117	330,499	324,428
Operating income	40,988		27,526		29,702		32,428		29,854		8,584		36,171		29,548		130,644	104,157	133,830
Net income	$ 27,245		$ 30,802		$ 27,152		$ 19,289		$ 22,863		$ 11,324		$ 28,684		$ 19,995		$ 104,488	$ 80,866	$ 98,100
Basic (in dollars per share)	$ 1.20		$ 1.36		$ 1.21		$ 0.86		$ 0.93		$ 0.50		$ 1.26		$ 0.88
Diluted (in dollars per share)	$ 1.19		$ 1.35		$ 1.20		$ 0.85		$ 0.92		$ 0.50		$ 1.26		$ 0.88

[1] In the fourth quarter of 2016, the company recorded ($0.1) million gain related to the company's transfer of its reed sensor manufacturing operations from the U.S. and China to the Philippines, $1.2 million of restructuring costs, $3.2 million in acquisition and integration costs and $0.3 million in non-cash inventory charges related to the 2016 acquisitions.

[2] In the third quarter of 2016, the company recorded $0.9 million of restructuring costs, $5.9 million in acquisition and integration costs, $14.8 million of charges related to the impairment of the custom products reporting unit and $0.5 million in non-cash inventory charges as noted above.

[3] In the second quarter of 2016, the company recorded $0.7 million related to the reed sensor manufacturing transfer as noted above, $0.1 million of restructuring costs, $6.1 million in acquisition and integration costs, $0.3 million in charges related to the closure of the manufacturing facility in Denmark and $6.9 million in non-cash inventory charges as noted above.

[4] In the first quarter of 2016, the company recorded $1.0 million related to the reed sensor manufacturing transfer as noted above, $0.4 million of restructuring costs, $6.2 million in acquisition and integration costs, and $1.6 million in charges related to the closure of the manufacturing facility in Denmark.

[5] In the fourth quarter of 2015, the company recorded $2.1 million related to the company's transfer of its reed switch manufacturing operations from the U.S. and China to the Philippines, ($0.1) million related to the reorganization of its internal legal structure, $4.0 million in acquisition costs, ($0.3) million in pension settlement refunds (See Note 10) and ($0.3) million in other.

[6] In the third quarter of 2015, the company recorded $1.2 million related to the reed switch manufacturing transfer as noted above, $0.9 million related to the company's reorganization of its internal legal structure as noted above, $0.3 million in acquisition costs, $30.8 million in pension settlement and wind-up costs (See Note 10) and $0.1 million in other.

[7] In the second quarter of 2015, the company recorded $0.9 million related to the reed switch manufacturing transfer as noted above, $1.7 million related to the company's reorganization of its internal legal structure as noted above, $0.2 million in acquisition costs, and $0.7 million in pension wind-up costs.

[8] In the first quarter of 2015, the company recorded $1.0 million related to the reed switch manufacturing transfer as noted above, $1.2 million in charges related to the reorganization of its internal legal structure as noted above, $0.2 million in acquisition costs, and $0.7 million in pension wind-up costs.