Note 5 - Loans and Allowance for Credit Losses - Loans Past Due (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Loans past due	$ 30,836	$ 31,082
Current loans	5,794,110	5,646,811
Total recorded investment in loans	5,824,946	5,677,893
Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due	11,335	7,608
Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due	5,146	5,599
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due	14,355	17,875
Commercial Portfolio Segment [Member]
Loans past due	5,297	4,881
Current loans	1,230,535	1,195,847
Total recorded investment in loans	1,235,832	1,200,728
Commercial Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due	1,663	1,634
Commercial Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due	1,191	757
Commercial Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due	2,443	2,490
Income Producing Portfolio Segment [Member]
Loans past due	7,780	11,050
Current loans	2,530,954	2,498,467
Total recorded investment in loans	2,538,734	2,509,517
Income Producing Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due		511
Income Producing Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due	2,158
Income Producing Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due	5,622	10,539
Owner Occupied Portfolio Segment [Member]
Loans past due	9,238	9,408
Current loans	628,894	631,462
Total recorded investment in loans	638,132	640,870
Owner Occupied Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due	5,733	3,987
Owner Occupied Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due	874	3,328
Owner Occupied Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due	2,631	2,093
Residential Portfolio Segment [Member]
Loans past due	1,484	1,733
Current loans	153,537	151,015
Total recorded investment in loans	155,021	152,748
Residential Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due	1,012	1,015
Residential Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due	162	163
Residential Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due	310	555
Construction Portfolio Segment [Member]
Loans past due	6,276	3,774
Current loans	1,145,857	1,054,795
Total recorded investment in loans	1,152,133	1,058,569
Construction Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due	2,863	360
Construction Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due	158	1,342
Construction Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due	3,255	2,072
Home Equity Portfolio Segment [Member]
Loans past due	644
Current loans	99,621	105,096
Total recorded investment in loans	100,265	105,096
Home Equity Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due	48
Home Equity Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due	596
Home Equity Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due
Other Consumer Portfolio Segment [Member]
Loans past due	117	236
Current loans	4,712	10,129
Total recorded investment in loans	4,829	10,365
Other Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due	16	101
Other Consumer Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due	7	9
Other Consumer Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due	$ 94	$ 126