Note 4 - Loans and Allowance for Loan Losses (Details) - Activity in Allowance for Loan Losses and the Recorded Investments in Loans (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Total loans:
Loans	$ 2,120,760,000		$ 2,089,277,000
Provision for loan losses	(400,000)	(1,900,000)
Commercial Portfolio Segment [Member] | Originated Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	17,736,000	20,455,000
Allowance for loan losses	18,977,000	19,001,000
Allowance for loan losses: individually evaluated for impairment	10,158,000	9,508,000
Allowance for loan losses: collectively evaluated for impairment	8,819,000	9,493,000
Total loans:
Loans	1,230,841,000	1,004,218,000	1,153,189,000
Loans: individually evaluated for impairment	44,257,000	29,883,000
Loans: collectively evaluated for impairment	1,186,584,000	974,335,000
Provision for loan losses	(499,000)	(1,454,000)
Charge-offs	(78,000)	(586,000)
Recoveries	1,818,000	586,000
Commercial Portfolio Segment [Member] | Acquired Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	681,000
Allowance for loan losses	622,000
Total loans:
Loans	528,508,000		562,114,000
Provision for loan losses	(60,000)
Charge-offs	0
Recoveries	1,000
Commercial Portfolio Segment [Member]
Total loans:
Loans	1,759,349,000		1,715,303,000
Retail Loan [Member] | Originated Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	1,487,000	2,358,000
Allowance for loan losses	1,235,000	1,957,000
Allowance for loan losses: individually evaluated for impairment	208,000	971,000
Allowance for loan losses: collectively evaluated for impairment	1,027,000	986,000
Total loans:
Loans	97,872,000	62,578,000
Loans: individually evaluated for impairment	1,193,000	3,512,000
Loans: collectively evaluated for impairment	96,679,000	59,066,000
Provision for loan losses	79,000	(434,000)
Charge-offs	(363,000)	(2,000)
Recoveries	32,000	35,000
Retail Loan [Member] | Acquired Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	61,000
Allowance for loan losses	177,000
Total loans:
Provision for loan losses	117,000
Charge-offs	(7,000)
Recoveries	6,000
Unallocated Financing Receivables [Member] | Originated Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	76,000	8,000
Allowance for loan losses	39,000	(4,000)
Allowance for loan losses: individually evaluated for impairment	0	0
Allowance for loan losses: collectively evaluated for impairment	39,000	(4,000)
Total loans:
Provision for loan losses	(37,000)	(12,000)
Charge-offs	0	0
Recoveries	0	0
Unallocated Financing Receivables [Member] | Acquired Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	0
Allowance for loan losses	0
Total loans:
Provision for loan losses	0
Charge-offs	0
Recoveries	0
Originated Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	19,299,000	22,821,000
Allowance for loan losses	20,251,000	20,954,000
Allowance for loan losses: individually evaluated for impairment	10,366,000	10,479,000
Allowance for loan losses: collectively evaluated for impairment	9,885,000	10,475,000
Total loans:
Loans	1,328,713,000	1,066,796,000	1,246,116,000
Loans: individually evaluated for impairment	45,450,000	33,395,000
Loans: collectively evaluated for impairment	1,283,263,000	1,033,401,000
Provision for loan losses	(457,000)	(1,900,000)
Charge-offs	(441,000)	(588,000)
Recoveries	1,850,000	621,000
Acquired Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	742,000
Allowance for loan losses	799,000
Total loans:
Loans	792,047,000		843,161,000
Provision for loan losses	57,000
Charge-offs	(7,000)
Recoveries	$ 7,000