Note 9 - Acquisition of Community State Bank and Common Stock Offering (Details Textual)		3 Months Ended			6 Months Ended
	May 23, 2016 USD ($) $ / shares shares	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
CSB [Member]
Number of Branches			10		10
Assets			$ 571,000,000		$ 571,000,000
Loans and Leases Receivable, Gross			433,000,000		433,000,000
Deposits			481,000,000		481,000,000
CSB [Member] | Scenario, Forecast [Member]
Business Acquisition, Percentage of Voting Interests Acquired		100.00%
Business Combination, Consideration Transferred		$ 80,000,000
Dividends, Cash		15,000,000
CSB [Member]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares	1,215,000
Business Acquisition, Share Price | $ / shares	$ 24.75
Business Combination, Acquisition Related Costs			355,000
Scenario, Forecast [Member] | Revolving Credit Facility [Member]
Proceeds from Lines of Credit		$ 5,000,000
Revolving Credit Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity			10,000,000		10,000,000		$ 40,000,000
Assets			2,683,434,288	$ 2,542,968,846	2,683,434,288	$ 2,542,968,846	2,593,198,275
Loans and Leases Receivable, Gross			1,922,773,397		1,922,773,397		1,798,022,675
Deposits			1,973,593,784		1,973,593,784		$ 1,880,666,184
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned	$ 30,000,000
Notes Payable			30,000,000		30,000,000
Business Combination, Acquisition Related Costs			$ 354,969		$ 354,969