Note 8 - Earnings Per Share (Details) - Calculation of Earnings Per Share (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Common Class A [Member] | Employee Stock Option [Member]
Weighted average effect of dilutive securities:
Weighted average effect of dilutive securities	404	481	381	519
Common Class A [Member] | Restricted Stock [Member]
Weighted average effect of dilutive securities:
Weighted average effect of dilutive securities	35	29	35	42
Common Class A [Member]
Numerator for net income per share - basic:
Allocation of distributed earnings (in Dollars)		$ 887	$ 1,071	$ 2,649
Allocation of undistributed earnings (in Dollars)	1,906	901	4,787	3,034
Net income attributable to common shareholders (in Dollars)	1,906	1,788	5,858	5,683
Denominator for net income per share - basic:
Weighted average common shares outstanding - basic	20,672	20,373	20,671	20,262
Weighted average effect of dilutive securities:
Weighted average common shares outstanding - diluted	21,111	20,883	21,087	20,823
Net income per share - diluted (in Dollars per share)	$ 0.09	$ 0.09	$ 0.28	$ 0.27
Net income per share - basic (in Dollars per share)	$ 0.09	$ 0.09	$ 0.28	$ 0.28
Numerator for net income per share - diluted:
Net income attributable to common shareholders for basic computation (in Dollars)	1,906	1,788	5,858	5,683
Common Class B [Member] | Employee Stock Option [Member]
Weighted average effect of dilutive securities:
Weighted average effect of dilutive securities	63	80	62	86
Common Class B [Member] | Restricted Stock [Member]
Weighted average effect of dilutive securities:
Weighted average effect of dilutive securities	6	5	6	7
Common Class B [Member]
Numerator for net income per share - basic:
Allocation of distributed earnings (in Dollars)		887	1,071	2,649
Allocation of undistributed earnings (in Dollars)	1,906	901	4,787	3,034
Net income attributable to common shareholders (in Dollars)	1,906	1,788	5,858	5,683
Denominator for net income per share - basic:
Weighted average common shares outstanding - basic	3,445	3,395	3,445	3,377
Weighted average effect of dilutive securities:
Weighted average common shares outstanding - diluted	3,514	3,480	3,513	3,470
Net income per share - diluted (in Dollars per share)	$ 0.54	$ 0.51	$ 1.67	$ 1.64
Net income per share - basic (in Dollars per share)	$ 0.55	$ 0.53	$ 1.70	$ 1.68
Numerator for net income per share - diluted:
Net income attributable to common shareholders for basic computation (in Dollars)	$ 1,906	$ 1,788	$ 5,858	$ 5,683