Note 6 - Earnings per Share (Detail) - Summary of Earnings and Weighted Average Number of Common Shares Used in the Calculation of Basic and Diluted Earnings Per Share (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Basic:
Weighted average common shares outstanding, basic	13,861,584	13,840,079
Dilutive effect of contingent issuable stock	233,000	50,143
Assumed average common shares outstanding	14,111,752	13,908,274
Net income (in Dollars)	$ 13,805	$ 12,654
Dividends to preferred stockholders (in Dollars)	2,168	2,168
Net income available to common stockholders (in Dollars)	$ 11,637	$ 10,486
Earnings per common share, basic (in Dollars per share)	$ 0.84	$ 0.76
Earnings per common share, diluted (in Dollars per share)	$ 0.82	$ 0.75
Stock Options [Member]
Basic:
Dilutive effect of securities	9,799	9,874
Restricted Stock [Member]
Basic:
Dilutive effect of securities	7,369	8,178