Note 4 - Loans and Allowance for Credit Losses (Detail) - Changes in the carrying amount of impaired purchased loans (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Purchased Covered Loans [Member]
Carrying amount at the beginning of the period	$ 18,591	$ 33,556
Reductions during the period	(10,726)	(14,965)
Carrying amount at the end of the period	7,865	18,591
Purchased Non-Covered Loans [Member]
Carrying amount at the beginning of the period	15,572	33,725
Reductions during the period	(8,808)	(18,153)
Carrying amount at the end of the period	$ 6,764	$ 15,572