Note 7 - Portfolio by Risk Rating (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Pass [Member] | Commercial Portfolio Segment [Member]
Loans	$ 2,017,005	$ 2,143,270
Pass [Member] | Real Estate Construction Portfolio Segment [Member]
Loans	461,282	413,765
Pass [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans	5,156,885	5,018,199
Pass [Member] | Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans	2,307,970	2,091,434
Pass [Member] | Consumer Portfolio Segment [Member]
Loans	3,180	2,493
Pass [Member]
Loans	9,946,322	9,669,161
Loans held for sale		732
Loans held for sale		732
Special Mention [Member] | Commercial Portfolio Segment [Member]
Loans	91,097	110,338
Special Mention [Member] | Real Estate Construction Portfolio Segment [Member]
Loans	14,457	5,776
Special Mention [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans	246,844	155,553
Special Mention [Member] | Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans	394	399
Special Mention [Member] | Consumer Portfolio Segment [Member]
Loans
Special Mention [Member]
Loans	352,792	272,066
Loans held for sale
Loans held for sale
Substandard [Member] | Commercial Portfolio Segment [Member]
Loans	78,910	61,297
Substandard [Member] | Real Estate Construction Portfolio Segment [Member]
Loans	5,581	21,502
Substandard [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans	119,300	118,196
Substandard [Member] | Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans	10,503	9,502
Substandard [Member] | Consumer Portfolio Segment [Member]
Loans
Substandard [Member]
Loans	214,294	210,497
Loans held for sale	2,925	5,944
Loans held for sale	2,925	5,944
Doubtful [Member] | Commercial Portfolio Segment [Member]
Loans	1,035	1,958
Doubtful [Member] | Real Estate Construction Portfolio Segment [Member]
Loans	500	500
Doubtful [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans	8,157	9,270
Doubtful [Member] | Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans
Doubtful [Member] | Consumer Portfolio Segment [Member]
Loans
Doubtful [Member]
Loans	9,692	11,728
Loans held for sale
Loans held for sale
Commercial Portfolio Segment [Member]
Loans	2,188,047	2,316,863
Real Estate Construction Portfolio Segment [Member]
Loans	481,820	441,543
Commercial Real Estate Portfolio Segment [Member]
Loans	5,531,186	5,301,218
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans	2,318,867	2,101,335
Consumer Portfolio Segment [Member]
Loans	3,180	2,493
Loans	10,523,100	10,163,452
Loans held for sale	2,925	6,676
Loans held for sale	$ 2,925	$ 6,676