Note 3 - Loans and Allowance for Loan Losses - Activity in Allowance for Loan Losses and the Recorded Investments in Loans (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Originated Loan [Member] | Commercial Portfolio Segment [Member]
Balance	$ 13,924,000	$ 18,977,000	$ 13,672,000	$ 17,736,000
Provision for loan losses	842,000	(1,151,000)	936,000	(1,651,000)
Charge-offs	(166,000)	(4,199,000)	(255,000)	(4,277,000)
Recoveries	129,000	365,000	376,000	2,184,000
Ending balance	14,729,000	13,992,000	14,729,000	13,992,000
Ending balance: individually evaluated for impairment	827,000	2,146,000	827,000	2,146,000
Ending balance: collectively evaluated for impairment	13,902,000	11,846,000	13,902,000	11,846,000
Loans	1,664,745,000	1,322,388,000	1,664,745,000	1,322,388,000	$ 1,493,516,000
Ending balance: individually evaluated for impairment	16,905,000	19,108,000	16,905,000	19,108,000
Ending balance: collectively evaluated for impairment	1,647,840,000	1,303,280,000	1,647,840,000	1,303,280,000
Originated Loan [Member] | Retail Portfolio Segment [Member]
Balance	1,834,000	1,235,000	1,421,000	1,487,000
Provision for loan losses	296,000	513,000	799,000	592,000
Charge-offs	(231,000)	(154,000)	(617,000)	(517,000)
Recoveries	14,000	120,000	310,000	152,000
Ending balance	1,913,000	1,714,000	1,913,000	1,714,000
Ending balance: individually evaluated for impairment	209,000	178,000	209,000	178,000
Ending balance: collectively evaluated for impairment	1,704,000	1,536,000	1,704,000	1,536,000
Loans	135,209,000	107,235,000	135,209,000	107,235,000	123,071,000
Ending balance: individually evaluated for impairment	1,463,000	1,180,000	1,463,000	1,180,000
Ending balance: collectively evaluated for impairment	133,746,000	106,055,000	133,746,000	106,055,000
Originated Loan [Member] | Unallocated Financing Receivables [Member]
Balance	214,000	39,000	140,000	76,000
Provision for loan losses	20,000	(5,000)	94,000	(42,000)
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	234,000	34,000	234,000	34,000
Ending balance: individually evaluated for impairment	0	0	0	0
Ending balance: collectively evaluated for impairment	234,000	34,000	234,000	34,000
Loans
Originated Loan [Member]
Balance	15,972,000	20,251,000	15,233,000	19,299,000
Provision for loan losses	1,158,000	(643,000)	1,829,000	(1,101,000)
Charge-offs	(397,000)	(4,353,000)	(872,000)	(4,794,000)
Recoveries	143,000	485,000	686,000	2,336,000
Ending balance	16,876,000	15,740,000	16,876,000	15,740,000
Ending balance: individually evaluated for impairment	1,036,000	2,324,000	1,036,000	2,324,000
Ending balance: collectively evaluated for impairment	15,840,000	13,416,000	15,840,000	13,416,000
Loans	1,799,954,000	1,429,623,000	1,799,954,000	1,429,623,000	1,616,587,000
Ending balance: individually evaluated for impairment	18,368,000	20,288,000	18,368,000	20,288,000
Ending balance: collectively evaluated for impairment	1,781,586,000	1,409,335,000	1,781,586,000	1,409,335,000
Acquired Loan [Member] | Commercial Portfolio Segment [Member]
Balance	266,000	622,000	420,000	681,000
Provision for loan losses	(57,000)	(31,000)	(167,000)	(90,000)
Charge-offs	0	(30,000)	0	(31,000)
Recoveries	2,000	0		1,000
Ending balance	211,000	561,000	211,000	561,000
Loans	395,010,000		395,010,000		453,180,000
Recoveries			(42,000)
Acquired Loan [Member] | Retail Portfolio Segment [Member]
Balance	24,000	177,000	28,000	61,000
Provision for loan losses	(1,000)	74,000	38,000	191,000
Charge-offs	0	0	0	(7,000)
Recoveries	0	9,000		15,000
Ending balance	23,000	260,000	23,000	260,000
Loans	184,976,000		184,976,000		207,960,000
Recoveries			(43,000)
Acquired Loan [Member] | Unallocated Financing Receivables [Member]
Balance	0	0	0	0
Provision for loan losses	0	0	0	0
Charge-offs	0	0	0	0
Recoveries	0	0		0
Ending balance	0	0	0	0
Recoveries			0
Acquired Loan [Member]
Balance	290,000	799,000	448,000	742,000
Provision for loan losses	(58,000)	43,000	(129,000)	101,000
Charge-offs	0	(30,000)	0	(38,000)
Recoveries	2,000	9,000		16,000
Ending balance	234,000	821,000	234,000	821,000
Loans	579,986,000		579,986,000		661,140,000
Recoveries			(85,000)
Commercial Portfolio Segment [Member]
Loans	2,059,755,000		2,059,755,000		1,946,696,000
Retail Portfolio Segment [Member]
Loans	320,185,000		320,185,000		331,031,000
Provision for loan losses	1,100,000	$ (600,000)	1,700,000	$ (1,000,000)
Loans	$ 2,379,940,000		$ 2,379,940,000		$ 2,277,727,000