Note 5 - Loans - Portfolio by Risk Rating (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Loans	$ 11,201,275	$ 10,163,452
Loans held for sale	7,500	6,676
Commercial Portfolio Segment [Member]
Loans	2,248,187	2,316,863
Real Estate Construction Portfolio Segment [Member]
Loans	548,088	441,543
Commercial Real Estate Portfolio Segment [Member]
Loans	5,785,248	5,301,218
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans	2,615,759	2,101,335
Consumer Portfolio Segment [Member]
Loans	3,993	2,493
Pass [Member]
Loans	10,513,473	9,669,161
Loans held for sale		732
Pass [Member] | Commercial Portfolio Segment [Member]
Loans	2,023,114	2,143,270
Pass [Member] | Real Estate Construction Portfolio Segment [Member]
Loans	469,909	413,765
Pass [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans	5,410,623	5,018,199
Pass [Member] | Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans	2,605,834	2,091,434
Pass [Member] | Consumer Portfolio Segment [Member]
Loans	3,993	2,493
Special Mention [Member]
Loans	435,032	272,066
Loans held for sale
Special Mention [Member] | Commercial Portfolio Segment [Member]
Loans	140,682	110,338
Special Mention [Member] | Real Estate Construction Portfolio Segment [Member]
Loans	44,129	5,776
Special Mention [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans	250,221	155,553
Special Mention [Member] | Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans		399
Special Mention [Member] | Consumer Portfolio Segment [Member]
Loans
Substandard [Member]
Loans	252,672	210,497
Loans held for sale	7,500	5,944
Substandard [Member] | Commercial Portfolio Segment [Member]
Loans	84,293	61,297
Substandard [Member] | Real Estate Construction Portfolio Segment [Member]
Loans	34,050	21,502
Substandard [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans	124,404	118,196
Substandard [Member] | Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans	9,925	9,502
Substandard [Member] | Consumer Portfolio Segment [Member]
Loans
Doubtful [Member]
Loans	98	11,728
Loans held for sale
Doubtful [Member] | Commercial Portfolio Segment [Member]
Loans	98	1,958
Doubtful [Member] | Real Estate Construction Portfolio Segment [Member]
Loans		500
Doubtful [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans		9,270
Doubtful [Member] | Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans
Doubtful [Member] | Consumer Portfolio Segment [Member]
Loans