Note 12 - Segment Information - Segment Information (Details) - USD ($) $ in Thousands		3 Months Ended																12 Months Ended
		Dec. 30, 2017	[1]	Sep. 30, 2017	[2]	Jul. 01, 2017	[3]	Apr. 01, 2017	[4]	Dec. 31, 2016	[5]	Oct. 01, 2016	[6]	Jul. 02, 2016	[7]	Apr. 02, 2016	[8]	Dec. 30, 2017	Dec. 31, 2016	Jan. 02, 2016
Net sales		$ 304,849		$ 317,889		$ 313,355		$ 285,441		$ 284,518		$ 280,331		$ 271,912		$ 219,398		$ 1,221,534	$ 1,056,159	$ 867,864
Depreciation and amortization																		63,011	53,137	41,641
Operating income		$ 50,780		$ 58,609		$ 60,270		$ 48,852		$ 40,988		$ 27,526		$ 29,702		$ 32,428		218,511	130,644	104,157
Interest expense																		13,380	8,628	4,091
Foreign exchange loss (gain)																		2,376	472	(1,465)
Other (income) expense, net																		(1,282)	(1,730)	(5,417)
Income before income taxes																		204,037	123,274	106,948
Electronics [Member]
Net sales																		661,928	535,191	405,497
Depreciation and amortization																		35,215	29,141	22,936
Operating income																		155,880	117,088	78,194
Automotive [Member]
Net sales																		453,227	415,200	339,957
Depreciation and amortization																		22,459	18,107	13,437
Operating income																		62,571	59,905	53,086
Industrial [Member]
Net sales																		106,379	105,768	122,410
Depreciation and amortization																		5,337	5,889	5,268
Operating income																		10,334	3,615	18,094
Other Segments [Member]
Operating income	[9]																	$ (10,274)	$ (49,964)	$ (45,217)

[1] In the fourth quarter of 2017, the Company recorded an estimated one-time tax charge of $49 million for the enactment of the Tax Cuts and Jobs Act for deemed repatriation of unremitted earnings of foreign subsidiaries, $1.4 million in acquisition and integration costs and $0.7 million in restructuring and production costs related to the transfer of Asian operations.

[2] In the third quarter of 2017, the Company recorded $4.8 million in acquisition and integration costs and $1.5 million in restructuring and production costs related to the transfer of Asian operations.

[3] In the second quarter of 2017, the Company recorded $0.3 million in acquisition and integration costs.

[4] In the first quarter of 2017, the Company $1.5 million in acquisition and integration costs

[5] 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.

[6] 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.

[7] 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.

[8] 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.

[9] Included in "Other" Operating income (loss) for 2017 are costs related to the acquisition and integration costs associated with the Company's completed and pending acquisitions ($8.0 million in Cost of sales ("COS") and Selling, general, and administrative expenses ("SG&A") and charges related to restructuring and production transfers in the Company's Asia operations ($2.2 million in SG&A). Included in "Other" Operating income (loss) for 2016 are costs related to the impairment of the Custom Products reporting unit ($14.8 million), acquisition and integration costs associated with the Company's 2016 acquisitions ($29.2 million in COS and SG&A), transfer of the Company's reed switch manufacturing operations from its Lake Mills, Wisconsin and Suzhou, China locations to the Philippines ($1.6 million in COS), impairment and severance costs related to the closure of the Company's manufacturing facility in Denmark ($1.9 million in SG&A), and restructuring costs ($2.5 million in SG&A and Research and development expenses). Included in "Other" Operating income (loss) for 2015 are costs related to the transfer of the Company's reed switch manufacturing operations from its Lake Mills, Wisconsin and Suzhou, China locations to the Philippines ($5.2 million in COS), acquisition related fees ($4.6 million included in SG&A), pension settlement and other costs ($31.9 million in SG&A), and restructuring costs ($3.6 million in SG&A).