Note 3 - Loans and Allowance for Loan Losses - Retail Credit Exposure (Details) - USD ($)	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Originated Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 72,680,000	$ 67,816,000
Originated Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	74,835,000	55,255,000
Originated Loan [Member] | Retail Portfolio Segment [Member]
Loans	147,515,000	123,071,000	$ 117,390,000
Originated Loan [Member]
Loans	1,873,221,000	1,616,587,000	$ 1,519,710,000
Acquired Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	54,946,000	72,830,000
Acquired Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	115,880,000	135,130,000
Acquired Loan [Member] | Retail Portfolio Segment [Member]
Loans	170,826,000	207,960,000
Acquired Loan [Member]
Loans	533,156,000	661,140,000
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	127,626,000	140,646,000
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	190,715,000	190,385,000
Retail Portfolio Segment [Member]
Loans	318,341,000	331,031,000
Loans	$ 2,406,377,000	$ 2,277,727,000