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		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Originated Loan [Member] | Commercial Portfolio Segment [Member]
Balance	$ 14,729,000	$ 13,992,000	$ 13,672,000	$ 17,736,000
Provision for loan losses	493,000	9,000	1,429,000	(1,641,000)
Charge-offs	(1,000)	0	(256,000)	(4,276,000)
Recoveries	78,000	200,000	454,000	2,382,000
Ending balance	15,299,000	14,201,000	15,299,000	14,201,000
Ending balance: individually evaluated for impairment	754,000	1,657,000	754,000	1,657,000
Ending balance: collectively evaluated for impairment	14,545,000	12,544,000	14,545,000	12,544,000
Loans	1,725,706,000	1,402,320,000	1,725,706,000	1,402,320,000	$ 1,493,516,000
Ending balance: individually evaluated for impairment	15,708,000	17,835,000	15,708,000	17,835,000
Ending balance: collectively evaluated for impairment	1,709,998,000	1,384,485,000	1,709,998,000	1,384,485,000
Originated Loan [Member] | Retail Portfolio Segment [Member]
Balance	1,913,000	1,714,000	1,421,000	1,487,000
Provision for loan losses	329,000	(13,000)	1,128,000	578,000
Charge-offs	(290,000)	(46,000)	(907,000)	(563,000)
Recoveries	101,000	36,000	411,000	189,000
Ending balance	2,053,000	1,691,000	2,053,000	1,691,000
Ending balance: individually evaluated for impairment	286,000	170,000	286,000	170,000
Ending balance: collectively evaluated for impairment	1,767,000	1,521,000	1,767,000	1,521,000
Loans	147,515,000	117,390,000	147,515,000	117,390,000	123,071,000
Ending balance: individually evaluated for impairment	1,433,000	1,212,000	1,433,000	1,212,000
Ending balance: collectively evaluated for impairment	146,082,000	116,178,000	146,082,000	116,178,000
Originated Loan [Member] | Unallocated Financing Receivables [Member]
Balance	234,000	34,000	140,000	76,000
Provision for loan losses	(252,000)	(89,000)	(158,000)	(131,000)
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	(18,000)	(55,000)	(18,000)	(55,000)
Ending balance: individually evaluated for impairment	0	0	0	0
Ending balance: collectively evaluated for impairment	(18,000)	(55,000)	(18,000)	(55,000)
Originated Loan [Member]
Balance	16,876,000	15,740,000	15,233,000	19,299,000
Provision for loan losses	570,000	(93,000)	2,399,000	(1,194,000)
Charge-offs	(291,000)	(46,000)	(1,163,000)	(4,839,000)
Recoveries	179,000	236,000	865,000	2,571,000
Ending balance	17,334,000	15,837,000	17,334,000	15,837,000
Ending balance: individually evaluated for impairment	1,040,000	1,827,000	1,040,000	1,827,000
Ending balance: collectively evaluated for impairment	16,294,000	14,010,000	16,294,000	14,010,000
Loans	1,873,221,000	1,519,710,000	1,873,221,000	1,519,710,000	1,616,587,000
Ending balance: individually evaluated for impairment	17,141,000	19,047,000	17,141,000	19,047,000
Ending balance: collectively evaluated for impairment	1,856,080,000	1,500,663,000	1,856,080,000	1,500,663,000
Acquired Loan [Member] | Commercial Portfolio Segment [Member]
Balance	211,000	561,000	420,000	681,000
Provision for loan losses	(39,000)	(389,000)	(206,000)	(479,000)
Charge-offs	0	(87,000)	0	(118,000)
Recoveries	0	0		1,000
Ending balance	172,000	85,000	172,000	85,000
Loans	362,330,000		362,330,000		453,180,000
Recoveries			(42,000)
Acquired Loan [Member] | Retail Portfolio Segment [Member]
Balance	23,000	260,000	28,000	61,000
Provision for loan losses	69,000	(18,000)	107,000	173,000
Charge-offs	(72,000)	(49,000)	(72,000)	(56,000)
Recoveries	0	4,000		19,000
Ending balance	20,000	197,000	20,000	197,000
Loans	170,826,000		170,826,000		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	234,000	821,000	448,000	742,000
Provision for loan losses	30,000	(407,000)	(99,000)	(306,000)
Charge-offs	(72,000)	(136,000)	(72,000)	(174,000)
Recoveries	0	4,000		20,000
Ending balance	192,000	282,000	192,000	282,000
Loans	533,156,000		533,156,000		661,140,000
Recoveries			(85,000)
Commercial Portfolio Segment [Member]
Loans	2,088,036,000		2,088,036,000		1,946,696,000
Retail Portfolio Segment [Member]
Loans	318,341,000		318,341,000		331,031,000
Provision for loan losses	600,000	$ (500,000)	2,300,000	$ (1,500,000)
Loans	$ 2,406,377,000		$ 2,406,377,000		$ 2,277,727,000