Consolidated Statements of Stockholders' Equity (Parentheticals) - $ / shares	3 Months Ended	9 Months Ended
	Dec. 31, 2016	Sep. 30, 2017	Sep. 30, 2016
Additional Paid-in Capital [Member]
Stock issued for employee stock purchase plan, shares (in shares)		13,001	15,735
Common Stock [Member] | Citizens National Bank [Member]
Stock issued for acquisition, shares (in shares)			835,741
Common Stock [Member] | Hardeman County Investment Company, Inc. [Member]
Stock issued for acquisition, shares (in shares)		799,970
Common Stock [Member]
Stock issued for compensation plans, shares (in shares)	10,109	122,138	137,706
Retained Earnings [Member]
Cash dividends, per share (in dollars per share)	$ 0.24	$ 0.75	$ 0.72