Note 5 - Loans (Details) - Aging of Loan Portfolio (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Type of Loans:
Total	$ 8,084,563	$ 7,429,147	$ 7,059,212
Commercial Loans Member
Type of Loans:
30-59 Days Past Due	7,170	16,832
60-89 Days Past Due	16,562	1,610
Greater than 90 Days Past Due		630
Non-accrual Loans	21,232	19,958
Total Past Due	44,964	39,030
Loans Not Past Due	2,253,760	2,088,077
Total	2,298,724	2,127,107
Real Estate Construction Loans [Member]
Type of Loans:
60-89 Days Past Due		1,471
Greater than 90 Days Past Due	0	0
Non-accrual Loans	28,586	36,299
Total Past Due	28,586	37,770
Loans Not Past Due	193,115	143,180
Total	221,701	180,950	237,372
Commercial Mortgage Loans [Member]
Type of Loans:
30-59 Days Past Due	20,043	21,570
60-89 Days Past Due	7,862	3,627
Greater than 90 Days Past Due	982	0
Non-accrual Loans	19,621	35,704
Total Past Due	48,508	60,901
Loans Not Past Due	3,974,543	3,707,551
Total	4,023,051	3,768,452	3,748,897
Residential Mortgage And Equity Lines Member
Type of Loans:
30-59 Days Past Due	3,508	5,324
60-89 Days Past Due	832	1,972
Greater than 90 Days Past Due	0	0
Non-accrual Loans	13,744	11,941
Total Past Due	18,084	19,237
Loans Not Past Due	1,508,448	1,320,845
Total	1,526,532	1,340,082	1,186,969
Installment And Other Loans Member
Type of Loans:
30-59 Days Past Due	100	0
60-89 Days Past Due		0
Greater than 90 Days Past Due	0	0
Non-accrual Loans	0	0
Total Past Due	100	0
Loans Not Past Due	14,455	12,556
Total	14,555	12,556
Total [Member]
Type of Loans:
30-59 Days Past Due	30,821	43,726
60-89 Days Past Due	25,256	8,680
Greater than 90 Days Past Due	982	630
Non-accrual Loans	83,183	103,902
Total Past Due	140,242	156,938
Loans Not Past Due	7,944,321	7,272,209
Total	$ 8,084,563	$ 7,429,147