Note 4 - Loans and Allowance for Loan Losses (Detail) (USD $)	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Dec. 31, 2012 Risk Ratings 6,7, and 8 [Member]	Sep. 30, 2012 Risk Ratings 6,7, and 8 [Member]	Mar. 31, 2013 Loans Receivable [Member]	Dec. 31, 2012 Loans Receivable [Member]	Mar. 31, 2013 Student Loans [Member]	Dec. 31, 2012 Student Loans [Member]	Mar. 31, 2013 Restructured During Current Period [Member]
Loans and Leases Receivable, Gross					$ 1,850,000,000	$ 1,920,000,000	$ 31,835,000	$ 34,145,000
Percentage of Portfolio							97.00%
Impaired Financing Receivable, Recorded Investment	25,800,000	30,800,000
Impaired Financing Receivable, Related Allowance	3,100,000	2,800,000
Impaired Financing Receivable, Interest Income, Accrual Method	295,000
Impaired Financing Receivable, Average Recorded Investment	28,300,000
Financing Receivable, Modifications, Number of Contracts									1
Financing Receivable, Modifications, Pre-Modification Recorded Investment									321,000
Loans And Leases Receivable Classified			$ 39,000,000	$ 43,400,000