Note 7 - Loans (Details) - Aging of Loan Portfolio (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	$ 8,302,282	$ 8,084,563
Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	11,386	7,170
60-89 Days Past Due	610	16,562
Non-accrual Loans	13,806	21,232
Total Past Due	25,802	44,964
Loans Not Past Due	2,204,078	2,253,760
Total	2,229,880	2,298,724
Real Estate Construction Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	3,140
Non-accrual Loans	28,042	28,586
Total Past Due	31,182	28,586
Loans Not Past Due	222,650	193,115
Total	253,832	221,701
Commercial Mortgage Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	62,014	20,043
60-89 Days Past Due		7,862
Greater than 90 Days Past Due	974	982
Non-accrual Loans	17,042	19,621
Total Past Due	80,030	48,508
Loans Not Past Due	4,112,957	3,974,543
Total	4,192,987	4,023,051
Residential Mortgage And Equity Lines Member
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	5,881	3,508
60-89 Days Past Due		832
Non-accrual Loans	11,498	13,744
Total Past Due	17,379	18,084
Loans Not Past Due	1,596,246	1,508,448
Total	1,613,625	1,526,532
Installment And Other Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due		100
Total Past Due		100
Loans Not Past Due	11,958	14,455
Total	11,958	14,555
Total [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	82,421	30,821
60-89 Days Past Due	610	25,256
Greater than 90 Days Past Due	974	982
Non-accrual Loans	70,388	83,183
Total Past Due	154,393	140,242
Loans Not Past Due	8,147,889	7,944,321
Total	$ 8,302,282	$ 8,084,563