Note 4 - Loans and Allowance for Credit Losses (Detail) - Allowance for Credit Losses (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Sep. 30, 2012
Allowance for loan losses:
Balance at beginning of period	$ 30,234	$ 32,597		$ 30,354
Additions:
Provision	2,800	2,800
Deductions:
Chargeoffs	(3,769)	(4,698)
Recoveries	1,089	1,184
Net loan losses	(2,680)	(3,514)
Balance at end of period	30,354	31,883		30,354
Liability for off-balance sheet credit exposure	2,693	2,693
Total allowance for credit losses	33,047	34,576	32,927
Commercial [Member]
Allowance for loan losses:
Balance at beginning of period	6,445	6,012
Additions:
Provision	531	1,275
Deductions:
Chargeoffs	(1,902)	(862)
Recoveries	462	389
Net loan losses	(1,440)	(473)
Balance at end of period	5,536	6,814
Liability for off-balance sheet credit exposure	1,663	1,643
Total allowance for credit losses	7,199	8,457	8,179
Commercial Real Estate Loans [Member]
Allowance for loan losses:
Balance at beginning of period	10,063	10,611
Additions:
Provision	994	1,764
Deductions:
Chargeoffs	(113)	(948)
Recoveries	21
Net loan losses	(92)	(948)
Balance at end of period	10,965	11,427
Liability for off-balance sheet credit exposure	3
Total allowance for credit losses	10,968	11,427	10,072
Construction [Member]
Allowance for loan losses:
Balance at beginning of period	484	2,342
Additions:
Provision	(4)	411
Deductions:
Recoveries		2
Net loan losses		2
Balance at end of period	480	2,755
Liability for off-balance sheet credit exposure		26
Total allowance for credit losses	480	2,781	484
Residential Real Estate Loans [Member]
Allowance for loan losses:
Balance at beginning of period	380	781
Additions:
Provision	246	734
Deductions:
Chargeoffs	(87)	(870)
Net loan losses	(87)	(870)
Balance at end of period	539	645
Total allowance for credit losses	539	645	380
Consumer Installment And Other [Member]
Allowance for loan losses:
Balance at beginning of period	3,194	3,072
Additions:
Provision	281	627
Deductions:
Chargeoffs	(1,308)	(1,653)
Recoveries	601	779
Net loan losses	(707)	(874)
Balance at end of period	2,768	2,825
Liability for off-balance sheet credit exposure	453	189
Total allowance for credit losses	3,221	3,014	3,613
Purchased Covered Loans [Member]
Allowance for loan losses:
Balance at beginning of period	1,005
Additions:
Provision	87	490
Deductions:
Chargeoffs	(359)	(365)
Recoveries	5	14
Net loan losses	(354)	(351)
Balance at end of period	738	139
Total allowance for credit losses	738	139	1,005
Unallocated Financing Receivable [Member]
Allowance for loan losses:
Balance at beginning of period	8,663	9,779
Additions:
Provision	665	(2,501)
Deductions:
Balance at end of period	9,328	7,278
Liability for off-balance sheet credit exposure	574	835
Total allowance for credit losses	$ 9,902	$ 8,113	$ 9,194