Note 6 - Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Detail) - Impaired Loans Individually Evaluated by Class (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Impaired Loans	$ 168,092	$ 159,487
Commercial And Industrial [Member] | Loans With No Specific Related Allowance [Member]
Impaired Loans	15,648	10,801	[1]
Commercial And Industrial [Member] | Loans With A Related Allowance For Credit Losses [Member]
Impaired Loans	31,703	26,028
Commercial And Industrial [Member] | Unpaid Principal Balance [Member]
Impaired Loans	72,375	58,591
Commercial And Industrial [Member] | Allowance For Credit Losses Allocated [Member]
Impaired Loans	12,041	14,827
Agricultural [Member] | Loans With No Specific Related Allowance [Member]
Impaired Loans	411	556	[1]
Agricultural [Member] | Loans With A Related Allowance For Credit Losses [Member]
Impaired Loans	566
Agricultural [Member] | Unpaid Principal Balance [Member]
Impaired Loans	977	556
Agricultural [Member] | Allowance For Credit Losses Allocated [Member]
Impaired Loans	136
Office Retail And Industrial [Member] | Loans With No Specific Related Allowance [Member]
Impaired Loans	14,485	11,897
Office Retail And Industrial [Member] | Loans With A Related Allowance For Credit Losses [Member]
Impaired Loans	29,399	16,319
Office Retail And Industrial [Member] | Unpaid Principal Balance [Member]
Impaired Loans	55,898	33,785
Office Retail And Industrial [Member] | Allowance For Credit Losses Allocated [Member]
Impaired Loans	5,563	1,507
Multi-Family [Member] | Loans With No Specific Related Allowance [Member]
Impaired Loans	7,899	5,072	[1]
Multi-Family [Member] | Loans With A Related Allowance For Credit Losses [Member]
Impaired Loans		517
Multi-Family [Member] | Unpaid Principal Balance [Member]
Impaired Loans	13,135	11,265
Multi-Family [Member] | Allowance For Credit Losses Allocated [Member]
Impaired Loans		20
Residential Construction [Member] | Loans With No Specific Related Allowance [Member]
Impaired Loans	9,157	9,718	[1]
Residential Construction [Member] | Loans With A Related Allowance For Credit Losses [Member]
Impaired Loans	6,577	7,660
Residential Construction [Member] | Unpaid Principal Balance [Member]
Impaired Loans	31,291	33,124
Residential Construction [Member] | Allowance For Credit Losses Allocated [Member]
Impaired Loans	3,020	2,502
Commercial Construction [Member] | Loans With No Specific Related Allowance [Member]
Impaired Loans	6,938	19,019	[1]
Commercial Construction [Member] | Loans With A Related Allowance For Credit Losses [Member]
Impaired Loans	14,882	3,790
Commercial Construction [Member] | Unpaid Principal Balance [Member]
Impaired Loans	28,824	28,534
Commercial Construction [Member] | Allowance For Credit Losses Allocated [Member]
Impaired Loans	659	758
Other Commerical Real Estate [Member] | Loans With No Specific Related Allowance [Member]
Impaired Loans	11,079	26,027	[1]
Other Commerical Real Estate [Member] | Loans With A Related Allowance For Credit Losses [Member]
Impaired Loans	19,348	22,083
Other Commerical Real Estate [Member] | Unpaid Principal Balance [Member]
Impaired Loans	39,121	70,868
Other Commerical Real Estate [Member] | Allowance For Credit Losses Allocated [Member]
Impaired Loans	4,148	6,481
Total Commercial Real Estate [Member] | Loans With No Specific Related Allowance [Member]
Impaired Loans	49,558	71,733	[1]
Total Commercial Real Estate [Member] | Loans With A Related Allowance For Credit Losses [Member]
Impaired Loans	70,206	50,369
Total Commercial Real Estate [Member] | Unpaid Principal Balance [Member]
Impaired Loans	168,269	177,576
Total Commercial Real Estate [Member] | Allowance For Credit Losses Allocated [Member]
Impaired Loans	13,390	11,268
Total Impaired Loans Individually Evaluated For Impairment [Member] | Loans With No Specific Related Allowance [Member]
Impaired Loans	65,617	83,090	[1]
Total Impaired Loans Individually Evaluated For Impairment [Member] | Loans With A Related Allowance For Credit Losses [Member]
Impaired Loans	102,475	76,397
Total Impaired Loans Individually Evaluated For Impairment [Member] | Unpaid Principal Balance [Member]
Impaired Loans	241,621	236,723
Total Impaired Loans Individually Evaluated For Impairment [Member] | Allowance For Credit Losses Allocated [Member]
Impaired Loans	$ 25,567	$ 26,095

[1] No specific allowance for credit losses is allocated to these loans since they are deemed to be sufficiently collateralized or had charge-offs. However, while each component of the allowance for credit losses is determined separately, the entire balance is available for the entire loan portfolio.