Note 6 - Goodwill and Other Intangible Assets (Details Textual) - USD ($)	3 Months Ended	6 Months Ended
	Mar. 31, 2015	Jun. 30, 2016	Dec. 31, 2015	Feb. 27, 2015
Core Deposit Premium [Member] | Community First Bancshares Inc [Member]
Finite-lived Intangible Assets Acquired	$ 11,300,000
Core Deposit Premium [Member] | Liberty Bancshares, Inc. [Member]
Finite-lived Intangible Assets Acquired	14,600,000
Core Deposit Premium [Member]
Finite-Lived Intangible Asset, Useful Life		10 years
Books of Business Intangible [Member] | Community First Bancshares Inc [Member]
Finite-lived Intangible Assets Acquired	$ 420,000
Books of Business Intangible [Member] | Minimum [Member]
Finite-Lived Intangible Asset, Useful Life		10 years
Books of Business Intangible [Member] | Maximum [Member]
Finite-Lived Intangible Asset, Useful Life		15 years
Community First Bancshares Inc [Member]
Goodwill				$ 110,440,000
Liberty Bancshares, Inc. [Member]
Goodwill				$ 95,207,000
Goodwill		$ 327,686,000	$ 327,686,000