Note 3 - Loans Receivable and Related Allowance for Loan Losses - Analysis of Changes in Allowance for Loan Losses (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Balance at the beginning of the year	$ 6,127,000	$ 5,545,000
Provision for loan losses	1,280,000	903,000
Charge-offs	(989,000)	(366,000)
Recoveries	90,000	45,000
Balance at the end of the year	6,508,000	6,127,000
Individually evaluated for impairment			$ 12,000	$ 7,000
Acquired loans
Collectively evaluated for impairment			6,496,000	6,120,000
Total	6,508,000	6,127,000	6,508,000	6,127,000
Individually evaluated for impairment			468,000	1,916,000
Acquired loans	159,374,000	62,921,000
Collectively evaluated for impairment			555,330,000	518,524,000
Total			715,172,000	583,361,000
Residential Portfolio Segment [Member]
Balance at the beginning of the year	2,090,000	1,846,000
Provision for loan losses	176,000	284,000
Charge-offs	(71,000)	(40,000)
Recoveries	3,000
Balance at the end of the year	2,198,000	2,090,000
Individually evaluated for impairment			12,000	7,000
Acquired loans
Collectively evaluated for impairment			2,186,000	2,083,000
Total	2,090,000	2,090,000	2,198,000	2,090,000
Individually evaluated for impairment			389,000	425,000
Acquired loans	72,654,000	20,300,000
Collectively evaluated for impairment			222,362,000	201,098,000
Total			295,405,000	221,823,000
Home Equity Loans and Lines of Credit [Member]
Balance at the beginning of the year	646,000	633,000
Provision for loan losses	143,000	104,000
Charge-offs	(155,000)	(114,000)
Recoveries	14,000	23,000
Balance at the end of the year	648,000	646,000
Individually evaluated for impairment
Acquired loans
Collectively evaluated for impairment			648,000	646,000
Total	646,000	646,000	648,000	646,000
Individually evaluated for impairment			6,000	8,000
Acquired loans	13,750,000	10,873,000
Collectively evaluated for impairment			89,996,000	89,059,000
Total			103,752,000	99,940,000
Commercial Real Estate Portfolio Segment [Member]
Balance at the beginning of the year	2,753,000	2,314,000
Provision for loan losses	789,000	558,000
Charge-offs	(484,000)	(127,000)
Recoveries	48,000	8,000
Balance at the end of the year	3,106,000	2,753,000
Individually evaluated for impairment
Acquired loans
Collectively evaluated for impairment			3,106,000	2,753,000
Total	2,753,000	2,753,000	3,106,000	2,753,000
Individually evaluated for impairment			34,000	914,000
Acquired loans	56,690,000	27,404,000
Collectively evaluated for impairment			182,010,000	164,750,000
Total			238,734,000	193,068,000
Commercial Portfolio Segment [Member]
Balance at the beginning of the year	585,000	700,000
Provision for loan losses	(86,000)	(103,000)
Charge-offs		(14,000)
Recoveries	1,000	2,000
Balance at the end of the year	500,000	585,000
Individually evaluated for impairment
Acquired loans
Collectively evaluated for impairment			500,000	585,000
Total	585,000	585,000	500,000	585,000
Individually evaluated for impairment			39,000	569,000
Acquired loans	12,974,000	1,451,000
Collectively evaluated for impairment			52,996,000	56,921,000
Total			66,009,000	58,941,000
Consumer Portfolio Segment [Member]
Balance at the beginning of the year	53,000	52,000
Provision for loan losses	258,000	60,000
Charge-offs	(279,000)	(71,000)
Recoveries	24,000	12,000
Balance at the end of the year	56,000	53,000
Individually evaluated for impairment
Acquired loans
Collectively evaluated for impairment			56,000	53,000
Total	53,000	53,000	56,000	53,000
Individually evaluated for impairment
Acquired loans	$ 3,306,000	$ 2,893,000
Collectively evaluated for impairment			7,966,000	6,696,000
Total			$ 11,272,000	$ 9,589,000