Note 5 - Loans (Detail) - Aging of Loan Portfolio (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Total	$ 7,429,147	$ 7,059,212
Commercial Loans Member
30-59 Days Past Due	16,832	1,683
60-89 Days Past Due	1,610	0
Greater than 90 Days Past Due	630	0
Non-accrual Loans	19,958	30,661
Total Past Due	39,030	32,344
Loans Not Past Due	2,088,077	1,835,931
Total	2,127,107	1,868,275
Real Estate Construction Loans [Member]
30-59 Days Past Due		20,326
60-89 Days Past Due	1,471	0
Greater than 90 Days Past Due	0	0
Non-accrual Loans	36,299	46,012
Total Past Due	37,770	66,338
Loans Not Past Due	143,180	171,034
Total	180,950	237,372
Commercial Mortgage Loans [Member]
30-59 Days Past Due	21,570	13,627
60-89 Days Past Due	3,627	20,277
Greater than 90 Days Past Due	0	6,726
Non-accrual Loans	35,704	107,784
Total Past Due	60,901	148,414
Loans Not Past Due	3,707,551	3,600,483
Total	3,768,452	3,748,897
Residential Mortgage And Equity Lines Member
30-59 Days Past Due	5,324	5,871
60-89 Days Past Due	1,972	0
Greater than 90 Days Past Due	0	0
Non-accrual Loans	11,941	16,740
Total Past Due	19,237	22,611
Loans Not Past Due	1,320,845	1,164,358
Total	1,340,082	1,186,969
Installment And Other Loans Member
30-59 Days Past Due	0	0
60-89 Days Past Due		0
Greater than 90 Days Past Due	0	0
Non-accrual Loans	0	0
Total Past Due		0
Loans Not Past Due	12,556	17,699
Total	12,556	17,699
Total [Member]
30-59 Days Past Due	43,726	41,507
60-89 Days Past Due	8,680	20,277
Greater than 90 Days Past Due	630	6,726
Non-accrual Loans	103,902	201,197
Total Past Due	156,938	269,707
Loans Not Past Due	7,272,209	6,789,505
Total	$ 7,429,147	$ 7,059,212