Note 3 - Earnings Per Share (Details) - Earnings per common 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
Earnings per common share: [Abstract]
Net income, as reported (in Dollars)	$ 9,421		$ 9,365		$ 25,804		$ 25,131
Weighted average common shares outstanding	29,773		30,432		30,143		30,434
Weighted average common stock equivalents	32		30		25		30
Total weighted average common shares outstanding and common stock equivalents	29,805		30,462		30,168		30,464
Basic earnings per common share (in Dollars per share)	$ 0.32		$ 0.31		$ 0.86		$ 0.83
Diluted earnings per common share (1) (in Dollars per share)	$ 0.32	[1]	$ 0.31	[1]	$ 0.86	[1]	$ 0.82	[1]
Dividend payout ratio	40.60%		41.90%		45.30%		47.00%

[1] For the three months ended September 30, 2013, options to purchase 111,050 shares at an average exercise price of $19.56 were not included in the computation of diluted earnings per common share as they are anti-dilutive. For the nine months ended September 30, 2013, options to purchase 320,200 shares at an average exercise price of $18.33 were not included in the computation of diluted earnings per common share as they are anti-dilutive. For the three and nine months ended September 30, 2012, options to purchase 557,140 shares at an average exercise price of $17.62 were not included in the computation of diluted earnings per common share as they are anti-dilutive.