Note 6 - Investment Securities (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended		3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Corporate Debt Securities [Member] Continuous Unrealized Loss Twelve Months Or More [Member]	Sep. 30, 2012 Loss Decrease [Member]	Sep. 30, 2012 Loss Decrease [Member] Continuous Unrealized Loss Twelve Months Or More [Member] Corporate Debt Securities [Member]	Sep. 30, 2012 Loss Decrease [Member] Continuous Unrealized Loss Twelve Months Or More [Member] Corporate Debt Securities [Member]	Sep. 30, 2012 Continuous Unrealized Loss Twelve Months Or More [Member] Corporate Debt Securities [Member]	Sep. 30, 2012 Single Issuer Corporate Debt Security [Member]	Sep. 30, 2012 Corporate Debt Securities [Member]	Dec. 31, 2011 Corporate Debt Securities [Member]
Available-for-sale Securities, Gross Unrealized Losses	$ 1,400								$ 1,299	$ 1,537
Available-for-sale Securities, Change in Net Unrealized Holding Gain (Loss) before Taxes	458		203				238
Percent Change Unrealized Loss Investment Securities				25.00%	13.50%	15.50%
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	1,300
Available-for-sale Securities, Amortized Cost Basis	$ 582,159	$ 583,951						$ 4,500	$ 6,741	$ 7,901