Note 20 - Mergers and Acquisitions - Estimated Fair Value of Assets Acquired and Liabilities Assumed (Details) - USD ($)			9 Months Ended	12 Months Ended
	Oct. 01, 2018	Sep. 30, 2017	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017
Consideration paid:
Goodwill				$ (19,448,000)	$ (10,288,000)
Gain on bargain purchase					$ 1,316,000
Community First [Member]
Assets acquired:
Cash and cash equivalents	$ 3,986,000
Securities available for sale
Loans receivable	111,566,000
Federal bank stocks	190,000
Accrued interest receivable	288,000
Premises and equipment	1,321,000
Core deposit intangible	1,208,000
Prepaid expenses and other assets	3,341,000
Total assets acquired	121,900,000
Liabilities assumed:
Deposits	106,149,000
Overnight borrowings	1,200,000
Accrued interest payable	61,000
Accrued expenses and other liabilities	449,000
Total liabilities assumed	107,859,000
Identifiable net assets acquired	14,041,000
Consideration paid:
Cash	2,429,000
Total consideration	23,202,000
Goodwill	(9,161,000)			$ (9,200,000)
Total consideration	23,202,000
Community First [Member] | Preferred Stock [Member]
Consideration paid:
Stock	4,206,000
Community First [Member] | Previously Owned Common Stock of CFB [Member]
Consideration paid:
Stock	931,000
Community First [Member] | Common Stock [Member]
Consideration paid:
Stock	$ 15,636,000
Northern Hancock Bank & Trust Co. [Member]
Assets acquired:
Cash and cash equivalents		$ 2,539,000	$ 2,539,000
Loans receivable		18,480,000	18,480,000
Federal bank stocks		11,000	11,000
Accrued interest receivable		103,000	103,000
Premises and equipment		708,000	708,000
Core deposit intangible		167,000	167,000
Prepaid expenses and other assets		766,000	766,000
Total assets acquired		22,774,000	22,774,000
Liabilities assumed:
Deposits		19,748,000	19,748,000
Accrued interest payable		6,000	6,000
Accrued expenses and other liabilities		8,000	8,000
Total liabilities assumed		19,762,000	19,762,000
Identifiable net assets acquired		3,012,000	3,012,000
Consideration paid:
Cash		22,000	22,000
Stock		1,700,000	1,674,000
Total consideration			1,696,000
Total consideration			1,696,000
Gain on bargain purchase		$ 1,300,000	$ 1,316,000