Note 6 - Earnings Per Common Share (Detail) - Basic and diluted earnings per common share: (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Numerator:
Net income (in Dollars)	$ 7,719	$ 6,518	$ 7,584	$ 5,446	$ 7,663	$ 6,333	$ 6,194	$ 4,095	$ 27,267	$ 24,285	$ 19,742
Denominator:
Basic earnings per common share - weighted-average shares									22,064	21,979	21,927
Effect of dilutive stock options									86	96	104
Diluted earnings per common share - weighted-average shares and assumed conversions									22,150	22,075	22,031
Basic earnings per common share (in Dollars per share)	$ 0.35	$ 0.30	$ 0.34	$ 0.25	$ 0.35	$ 0.29	$ 0.28	$ 0.19	$ 1.24	$ 1.10	$ 0.90
Diluted earnings per common share (in Dollars per share)	$ 0.35	$ 0.29	$ 0.34	$ 0.25	$ 0.35	$ 0.29	$ 0.28	$ 0.19	$ 1.23	$ 1.10	$ 0.90