Note 7 - Loans (Detail) - Allowance for Loan Losses by Portfolio Segment (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Provision for possible credit losses	$ (37)	$ 2,740
Commercial Loans Member
Beginning Balance	66,101	65,658
Provision for possible credit losses	(3,310)	(1,041)
Charge-offs	(2,690)	(4,959)
Recoveries	955	746
Net charge-offs	(1,735)	(4,213)
Ending Balance	61,056	60,404
Reserve for impaired loans	1,717	1,272
Reserve for non-impaired loans	59,339	59,119
Reserve for off-balance sheet credit commitments	837	720
Real Estate Construction Loans [Member]
Beginning Balance	23,017	21,749
Provision for possible credit losses	(2,399)	(6,439)
Charge-offs	0	(875)
Recoveries	79	3,557
Net charge-offs	79	2,682
Ending Balance	20,697	17,992
Reserve for impaired loans	8,080	0
Reserve for non-impaired loans	12,617	17,993
Reserve for off-balance sheet credit commitments	311	635
Commercial Mortgage Loans [Member]
Beginning Balance	82,473	108,021
Provision for possible credit losses	2,968	4,318
Charge-offs	(990)	(8,222)
Recoveries	365	2,058
Net charge-offs	(625)	(6,164)
Ending Balance	84,816	106,175
Reserve for impaired loans	6,242	2,529
Reserve for non-impaired loans	78,574	103,657
Reserve for off-balance sheet credit commitments	2,122	84
Residential Mortgage And Equity Lines Member
Beginning Balance	11,703	10,795
Provision for possible credit losses	795	(260)
Charge-offs	(410)	(779)
Recoveries	3	366
Net charge-offs	(407)	(413)
Ending Balance	12,091	10,122
Reserve for impaired loans	1,318	1,806
Reserve for non-impaired loans	10,773	8,317
Reserve for off-balance sheet credit commitments	33	34
Installment And Other Loans Member
Beginning Balance	28	57
Provision for possible credit losses	4	15
Charge-offs		(25)
Recoveries		3
Net charge-offs		(22)
Ending Balance	32	50
Reserve for impaired loans		0
Reserve for non-impaired loans	32	50
Reserve for off-balance sheet credit commitments	2	2
Total [Member]
Beginning Balance	183,322	206,280
Provision for possible credit losses	(1,942)	(3,407)
Charge-offs	(4,090)	(14,860)
Recoveries	1,402	6,730
Net charge-offs	(2,688)	(8,130)
Ending Balance	178,692	194,743
Reserve for impaired loans	17,357	5,607
Reserve for non-impaired loans	161,335	189,136
Reserve for off-balance sheet credit commitments	$ 3,305	$ 1,475