Note 4 - Loans and Allowance for Credit Losses (Detail) (USD $)	3 Months Ended			3 Months Ended																						12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Mar. 31, 2013 Nonaccrual Loans [Member]	Mar. 31, 2013 Nonaccrual Loans Current and in Accordance with Original Terms [Member]	Dec. 31, 2012 Nonperforming Financing Receivable [Member]	Mar. 31, 2013 Performing Financing Receivable [Member]	Dec. 31, 2012 Performing Financing Receivable [Member]	Mar. 31, 2012 Performing Financing Receivable [Member]	Mar. 31, 2013 One TDR [Member]	Mar. 31, 2013 Commercial Real Estate Owner Occupied [Member]	Dec. 31, 2012 Commercial Real Estate Owner Occupied [Member]	Mar. 31, 2012 Commercial Real Estate Owner Occupied [Member]	Mar. 31, 2013 Commercial Real Estate and Real Estate Construction Loans [Member]	Mar. 31, 2013 Excluding Owner Occupied Commercial Real Estate And Commercial Construction Loans [Member]	Mar. 31, 2013 Commercial Loan [Member]	Dec. 31, 2012 Commercial Loan [Member]	Mar. 31, 2012 Commercial Loan [Member]	Mar. 31, 2013 SBA Loans [Member]	Mar. 31, 2013 Home Equity Line of Credit [Member]	Dec. 31, 2012 Home Equity Line of Credit [Member]	Mar. 31, 2012 Home Equity Line of Credit [Member]	Mar. 31, 2013 Residential Mortgage Loan Long-Term [Member]	Dec. 31, 2012 Commercial Land Acquisition Loans [Member]	Dec. 31, 2012 ADC Loans [Member]	Dec. 31, 2012 Maximum [Member]	Mar. 31, 2013 Maximum [Member]	Mar. 31, 2012 Maximum [Member]	Mar. 31, 2013 Minimum [Member]	Dec. 31, 2012 Minimum [Member]	Mar. 31, 2012 Minimum [Member]	Mar. 31, 2013 Construction Loans [Member]	Dec. 31, 2012 Construction Loans [Member]	Mar. 31, 2012 Construction Loans [Member]
Loans and Leases Receivable, Deferred Income	$ 9,100,000	$ 8,800,000
Servicing Asset at Fair Value, Amount	39,100,000	41,200,000
Percent Of Loan Portfolio											13.00%			70.00%	57.00%	23.00%			2.00%	4.00%			3.00%
Loan To Value Ratio																											80.00%
Minimum Debt Service Coverage (in Basis Points)																											0.0115%	0.0115%	0.01%		0.01%
Interest Rate Adjustment Frequency	5 years
Length Of Loan																	10 years						10 years	24 months		7 years				5 years			36 months
Stress Test Assumption Increase Interest Rates (in Basis Points)			2.00%
Amortization Term																										25 years
Financing Receivable, Net	2,548,024,000										303,561,000					579,618,000				108,570,000					572,100,000							572,073,000
	100.00%	100.00%	100.00%																						33.00%
Impaired Financing Receivable, Recorded Investment	42,980,000	43,098,000	45,997,000			2,000,000					6,449,000	6,659,000	207,000			7,993,000	9,248,000	7,117,000		481,000	513,000	392,000										21,959,000	23,235,000	26,213,000
Impaired Financing Receivable, Unpaid Principal Balance	43,480,000	48,096,000	48,322,000			11,700,000					6,449,000	6,659,000	277,000			8,493,000	9,461,000	8,382,000		481,000	513,000	530,000										21,959,000	25,347,000	29,013,000
Financing Receivable, Modifications, Recorded Investment							14,800,000	15,300,000	11,400,000	500,000
Interest and Fee Income, Loans and Leases	$ 36,024,000	$ 30,723,000		$ 0	$ 507,000,000