Note 7 - Loans (Detail) - Aging of Loan Portfolio (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Total	$ 7,364,340	$ 7,429,147
Commercial Loans Member
30-59 Days Past Due	15,766	16,832
60-89 Days Past Due	0	1,610
Greater than 90 Days Past Due	333	630
Non-accrual Loans	13,192	19,958
Total Past Due	29,291	39,030
Loans Not Past Due	2,002,498	2,088,077
Total	2,031,789	2,127,107
Real Estate Construction Loans [Member]
30-59 Days Past Due	634	0
60-89 Days Past Due	0	1,471
Greater than 90 Days Past Due	0	0
Non-accrual Loans	36,237	36,299
Total Past Due	36,871	37,770
Loans Not Past Due	147,196	143,180
Total	184,067	180,950
Commercial Mortgage Loans [Member]
30-59 Days Past Due	56,343	21,570
60-89 Days Past Due	4,133	3,627
Greater than 90 Days Past Due	467	0
Non-accrual Loans	39,221	35,704
Total Past Due	100,164	60,901
Loans Not Past Due	3,659,416	3,707,551
Total	3,759,580	3,768,452
Residential Mortgage And Equity Lines Member
30-59 Days Past Due	11,189	5,324
60-89 Days Past Due	1,134	1,972
Greater than 90 Days Past Due	0	0
Non-accrual Loans	11,679	11,941
Total Past Due	24,002	19,237
Loans Not Past Due	1,350,920	1,320,845
Total	1,374,922	1,340,082
Installment And Other Loans Member
30-59 Days Past Due	0	0
60-89 Days Past Due	0	0
Greater than 90 Days Past Due	0	0
Non-accrual Loans	0	0
Total Past Due	0	0
Loans Not Past Due	13,982	12,556
Total	13,982	12,556
Total [Member]
30-59 Days Past Due	83,932	43,726
60-89 Days Past Due	5,267	8,680
Greater than 90 Days Past Due	800	630
Non-accrual Loans	100,329	103,902
Total Past Due	190,328	156,938
Loans Not Past Due	7,174,012	7,272,209
Total	$ 7,364,340	$ 7,429,147