Note 9 - 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		6 Months Ended
	Jun. 29, 2013	Jun. 30, 2012	Jun. 29, 2013	Jun. 30, 2012
Computation of Basic and Diluted Earnings Per Share under the Two-class Method [Abstract]
Net income as reported	$ 26,648	$ 22,963	$ 41,442	$ 40,526
Less: Distributed earnings available to participating securities	(10)	(6)	(18)	(12)
Less: Undistributed earnings available to participating securities		(30)	(16)	(78)
Numerator for basic earnings per share —
Undistributed and distributed earnings available to common shareholders	26,638	22,927	41,408	40,436
Add: Undistributed earnings allocated to participating securities		30	15	78
Less: Undistributed earnings reallocated to participating securities		(30)	(15)	(77)
Numerator for diluted earnings per share —
Undistributed and distributed earnings available to common shareholders	$ 26,638	$ 22,927	$ 41,408	$ 40,437
Denominator for basic earnings per share —
Weighted-average shares (in Shares)	22,296	21,778	22,197	21,693
Effect of dilutive securities:
Common stock equivalents (in Shares)	203	296	234	310
Denominator for diluted earnings per share —
Adjusted for weighted-average shares & assumed conversions (in Shares)	22,499	22,074	22,431	22,004
Basic earnings per share (in Dollars per share)	$ 1.19	$ 1.05	$ 1.87	$ 1.86
Diluted earnings per share (in Dollars per share)	$ 1.18	$ 1.04	$ 1.85	$ 1.84