Note 7 - Loans (Detail) - Aging of Loan Portfolio (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Type of Loans:
Total	$ 7,043,683	$ 7,059,212
Commercial Loans Member
Type of Loans:
30-59 Days Past Due	0	1,683
60-89 Days Past Due	4,182	0
Greater than 90 Days Past Due	746	0
Non-accrual Loans	25,716	30,661
Total Past Due	30,644	32,344
Loans Not Past Due	1,915,076	1,835,931
Total	1,945,720	1,868,275
Real Estate Construction Loans [Member]
Type of Loans:
30-59 Days Past Due	10,689	20,326
60-89 Days Past Due	0	0
Greater than 90 Days Past Due	0	0
Non-accrual Loans	11,946	46,012
Total Past Due	22,635	66,338
Loans Not Past Due	157,451	171,034
Total	180,086	237,372
Commercial Mortgage Loans [Member]
Type of Loans:
30-59 Days Past Due	0	13,627
60-89 Days Past Due	20,362	20,277
Greater than 90 Days Past Due	0	6,726
Non-accrual Loans	70,630	107,784
Total Past Due	90,992	148,414
Loans Not Past Due	3,604,448	3,600,483
Total	3,695,440	3,748,897
Residential Mortgage And Equity Lines Member
Type of Loans:
30-59 Days Past Due	14,728	5,871
60-89 Days Past Due	18,853	0
Greater than 90 Days Past Due	0	0
Non-accrual Loans	14,530	16,740
Total Past Due	48,111	22,611
Loans Not Past Due	1,157,653	1,164,358
Total	1,205,764	1,186,969
Installment And Other Loans Member
Type of Loans:
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	16,673	17,699
Total	16,673	17,699
Total [Member]
Type of Loans:
30-59 Days Past Due	25,417	41,507
60-89 Days Past Due	43,397	20,277
Greater than 90 Days Past Due	746	6,726
Non-accrual Loans	122,822	201,197
Total Past Due	192,382	269,707
Loans Not Past Due	6,851,301	6,789,505
Total	$ 7,043,683	$ 7,059,212