Note 4 - Debt and Equity Securities (Detail) - Securities available for sale by contractual maturity: (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Due in one year or less	$ 22,823
Due in one year or less	22,823
Due after one year through five years	59,256
Due after one year through five years	62,081
Due after five years through ten years	49,774
Due after five years through ten years	51,110
Due after ten years	102,929
Due after ten years	99,579
Total other securities	234,782
Total other securities	235,593	229,453
Mortgage-backed securities	739,357
Mortgage-backed securities	764,701	720,113
Total securities available for sale	974,139	915,947
Total securities available for sale	$ 1,000,294	$ 949,566