Note 5 - Loans and Allowance for Credit Losses - Recorded Investment in Loans by Impairment Method (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Recorded investment in loans:
Loans individually evaluated for impairment	$ 29,935	$ 34,471	$ 40,591
Loans collectively evaluated for impairment	5,795,011	5,643,422	5,115,280
Net loans	5,824,946	5,677,893	5,155,871
Commercial Portfolio Segment [Member]
Recorded investment in loans:
Loans individually evaluated for impairment	10,873	10,437	13,161
Loans collectively evaluated for impairment	1,224,959	1,190,291	1,046,886
Net loans	1,235,832	1,200,728	1,060,047
Income Producing Portfolio Segment [Member]
Recorded investment in loans:
Loans individually evaluated for impairment	10,170	15,057	19,905
Loans collectively evaluated for impairment	2,528,564	2,494,460	2,118,186
Net loans	2,538,734	2,509,517	2,138,091
Owner Occupied Portfolio Segment [Member]
Recorded investment in loans:
Loans individually evaluated for impairment	2,631	2,093	1,724
Loans collectively evaluated for impairment	635,501	638,777	568,191
Net loans	638,132	640,870	569,915
Residential Portfolio Segment [Member]
Recorded investment in loans:
Loans individually evaluated for impairment		241	257
Loans collectively evaluated for impairment	155,021	152,507	148,902
Net loans	155,021	152,748	149,159
Construction Portfolio Segment [Member]
Recorded investment in loans:
Loans individually evaluated for impairment	6,167	6,517	5,422
Loans collectively evaluated for impairment	1,145,966	1,052,052	1,116,591
Net loans	1,152,133	1,058,569	1,122,013
Home Equity Portfolio Segment [Member]
Recorded investment in loans:
Loans individually evaluated for impairment			122
Loans collectively evaluated for impairment	100,265	105,096	110,863
Net loans	100,265	105,096	110,985
Other Consumer Portfolio Segment [Member]
Recorded investment in loans:
Loans individually evaluated for impairment	94	126
Loans collectively evaluated for impairment	4,735	10,239	5,661
Net loans	$ 4,829	$ 10,365	$ 5,661