Note 5 - Loans Acquired (Details Textual) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014
Liberty Bancshares, Inc. [Member] | Purchased Credit Impaired Loans [Member]
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed Other Noncurrent Assets Loans Acquired Not Covered By FDIC Loss Share		$ 10,700,000
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed Other Noncurrent Assets Loans Acquired Gross		15,700,000
Loans Acquired Discount		5,000,000
Liberty Bancshares, Inc. [Member]
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed Other Noncurrent Assets Loans Acquired Not Covered By FDIC Loss Share		769,900,000
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed Other Noncurrent Assets Loans Acquired Gross		774,800,000
Loans Acquired Discount		4,900,000
Community First Bancshares Inc [Member] | Purchased Credit Impaired Loans [Member]
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed Other Noncurrent Assets Loans Acquired Not Covered By FDIC Loss Share		7,000,000
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed Other Noncurrent Assets Loans Acquired Gross		10,100,000
Loans Acquired Discount		3,100,000
Community First Bancshares Inc [Member]
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed Other Noncurrent Assets Loans Acquired Not Covered By FDIC Loss Share		1,130,000,000
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed Other Noncurrent Assets Loans Acquired Gross		1,150,000,000
Loans Acquired Discount		23,700,000
Acquired Loans [Member]
Non Covered Impaired Loans Allowance Reclassified	$ 954,000		$ 954,000
FDIC Indemnification Asset, Accretion of Discount	0	40,000
Provision for Loan and Lease Losses		254,000	736,000
FDIC Indemnification Asset, Cash Payments Received	2,368,000
Gain (Loss) on Contract Termination	(7,476,000)
Non Covered Impaired Loans Allowance Reclassified	954,000		$ 954,000	$ 954,000
Covered Purchased Impaired Loans Allowance				$ 954,000
Provision for Loan and Lease Losses	$ 2,823,000	$ 1,171,000