Note 17 - Earnings Per Share (Details) - Computation of Basic and Diluted Earnings Per Share under the Two-class Method (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended															12 Months Ended
	Dec. 28, 2013		Sep. 28, 2013		Jun. 29, 2013		Mar. 30, 2013		Dec. 29, 2012		Sep. 29, 2012		Jun. 30, 2012	Mar. 31, 2012		Dec. 28, 2013	Dec. 29, 2012	Dec. 31, 2011
Computation of Basic and Diluted Earnings Per Share under the Two-class Method [Abstract]
Net income as reported	$ 23,658	[1]	$ 26,990	[2]	$ 26,648	[3]	$ 11,488	[3],[4]	$ 12,029	[4],[5]	$ 22,778	[5],[6]	$ 22,963	$ 17,563	[6],[7]	$ 88,784	$ 75,332	$ 87,024
Less: Distributed earnings available to participating securities																(35)	(30)	(16)
Less: Undistributed earnings available to participating securities																(16)	(98)	(288)
Numerator for basic earnings per share —
Undistributed and distributed earnings available to common shareholders																88,733	75,204	86,720
Add: Undistributed earnings allocated to participating securities																16	98	288
Less: Undistributed earnings reallocated to participating securities																(16)	(97)	(283)
Numerator for diluted earnings per share —
Undistributed and distributed earnings available to common shareholders																$ 88,733	$ 75,205	$ 86,725
Denominator for basic earnings per share —
Weighted-average shares (in Shares)																22,315	21,822	21,901
Effect of dilutive securities:
Common stock equivalents (in Shares)																222	276	354
Denominator for diluted earnings per share —
Adjusted for weighted-average shares & assumed conversions (in Shares)																22,537	22,098	22,255
Basic earnings per share (in Dollars per share)	$ 1.05	[1]	$ 1.20	[2]	$ 1.19	[3]	$ 0.52	[3],[4]	$ 0.55	[4],[5]	$ 1.04	[5],[6]	$ 1.05	$ 0.81	[6],[7]	$ 3.98	$ 3.45	$ 3.96
Diluted earnings per share (in Dollars per share)	$ 1.04	[1]	$ 1.19	[2]	$ 1.18	[3]	$ 0.51	[3],[4]	$ 0.53	[4],[5]	$ 1.03	[5],[6]	$ 1.04	$ 0.80	[6],[7]	$ 3.94	$ 3.40	$ 3.90

[1] In the fourth quarter of 2013, the company recorded a $2.8 million charge to income tax expense related to the company's impairment of its investment in Shocking Technologies in the fourth quarter of 2012. (See Note 6). The company also recorded a $0.5 million non-cash credit related to the step-up of inventory from the Hamlin acquisition (See Note 2) and $0.2 million in acquisition expenses for the Hamlin acquisition.

[2] In the third quarter of 2013, the company recorded a $0.3 million non-cash charge related to the step-up of inventory from the Hamlin acquisition (See Note 2). The company also recorded $0.3 million in acquisition charges related to the Hamlin acquisition.

[3] In the second quarter of 2013, the company recorded a $1.7 million non-cash charge related to step-up of inventory from the Hamlin acquisition (See Note 2). The company also recorded $1.2 million in acquisition charges related to the Hamlin acquisition.

[4] In the first quarter of 2013, the company recorded a $10.7 million charge related to the impairment of Shocking Technologies. Additionally, the company restated net income for a $3.3 million charge to income tax expense related to the company's investment in Shocking Technologies (See Note 6).

[5] In the fourth quarter of 2012, the company recorded a $7.3 million charge related to the impairment and equity method losses of Shocking Technologies. (See Note 6). The company also recorded a $5.1 million charge related to a pension settlement (See Note 12).

[6] In the third quarter of 2012, the company recorded $0.5 million charge related to the impairment of the Dnsen, Germany property (See Note 11). The company also recorded $0.6 million in acquisition charges related to the Accel and Terra Power acquisitions and $0.4 million of non-cash charges related to the step-up of inventory from the Accel acquisition (See Note 2).

[7] In the first quarter of 2012, the company recorded a $0.2 million non-cash charge related to the step-up of inventory from the Selco acquisition (See Note 2).