Note 3 - Loans and Allowance for Loan Losses - Retail Credit Exposure (Details) - USD ($)	Mar. 31, 2017	Dec. 31, 2016
Loans	$ 2,441,314,000	$ 2,378,620,000
Retail Portfolio Segment [Member]
Loans	317,966,000	313,273,000
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	112,117,000	118,047,000
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	205,849,000	195,226,000
Originated Loan [Member]
Loans	1,973,739,000	1,884,548,000
Originated Loan [Member] | Retail Portfolio Segment [Member]
Loans	170,330,000	155,650,000
Originated Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	69,032,000	69,831,000
Originated Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	101,298,000	85,819,000
Acquired Loan [Member]
Loans	467,575,000	494,072,000
Acquired Loan [Member] | Retail Portfolio Segment [Member]
Loans	147,636,000	157,623,000
Acquired Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	43,085,000	48,216,000
Acquired Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 104,551,000	$ 109,407,000