Note 3 - Loans and Allowance for Loan Losses - Retail Credit Exposure (Details) - USD ($)	Jun. 30, 2017	Dec. 31, 2016
Loans	$ 2,527,281,000	$ 2,378,620,000
Retail Portfolio Segment [Member]
Loans	328,688,000	313,273,000
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	107,991,000	118,047,000
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	220,697,000	195,226,000
Originated Loan [Member]
Loans	2,078,875,000	1,884,548,000
Originated Loan [Member] | Retail Portfolio Segment [Member]
Loans	190,745,000	155,650,000
Originated Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	69,788,000	69,831,000
Originated Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	120,957,000	85,819,000
Acquired Loan [Member]
Loans	448,406,000	494,072,000
Acquired Loan [Member] | Retail Portfolio Segment [Member]
Loans	137,943,000	157,623,000
Acquired Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	38,203,000	48,216,000
Acquired Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 99,740,000	$ 109,407,000