Note 2 - Correction of Immaterial Errors - Effects of Adjustments to Correct Immaterial Errors, Statements of Equity (Details) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2016		Oct. 01, 2016	[2]	Jul. 02, 2016	[3]	Apr. 02, 2016	[4]	Jan. 02, 2016		Sep. 26, 2015	[6]	Jun. 27, 2015	[7]	Mar. 28, 2015	[8]	Dec. 31, 2016	Jan. 02, 2016	Dec. 27, 2014	Dec. 28, 2013
Net income	$ 27,245	[1]	$ 30,802		$ 27,152		$ 19,289		$ 22,863	[5]	$ 11,324		$ 28,684		$ 19,995		$ 104,488	$ 80,866	$ 98,100
Comprehensive income																	75,580	56,321	56,557
Retained earnings	634,391								557,771								634,391	557,771
Stockholder's equity	814,931								739,252								814,931	739,252	724,319	$ 684,888
Retained Earnings [Member]
Net income																	104,488	80,866	98,100
Retained earnings									557,771									557,771	519,956	443,031
Stockholder's equity	$ 634,391								557,769								$ 634,391	557,769	519,956	443,031
Scenario, Previously Reported [Member]
Net income																		82,466	99,418
Comprehensive income																		57,921	57,875
Stockholder's equity									744,198									744,198	727,665	686,916
Scenario, Previously Reported [Member] | Retained Earnings [Member]
Retained earnings									562,717									562,717	523,302	445,059
Stockholder's equity																				445,059
Restatement Adjustment [Member]
Net income																		(1,600)	(1,318)
Comprehensive income																		(1,600)	(1,318)
Stockholder's equity									(4,946)									(4,946)	(3,346)	(2,028)
Restatement Adjustment [Member] | Retained Earnings [Member]
Retained earnings									$ (4,946)									$ (4,946)	$ (3,346)	(2,028)
Stockholder's equity																				$ (2,028)

[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.