Note 6 - Investment Securities (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended		3 Months Ended	6 Months Ended		3 Months Ended	6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 Corporate Debt Securities [Member] Continuous Unrealized Loss Twelve Months Or More [Member]	Jun. 30, 2012 Corporate Debt Securities [Member] Continuous Unrealized Loss Twelve Months Or More [Member]	Jun. 30, 2012 Loss Decrease [Member] Continuous Unrealized Loss Twelve Months Or More [Member]	Jun. 30, 2012 Loss Increase [Member] Continuous Unrealized Loss Twelve Months Or More [Member]	Jun. 30, 2012 Loss Decrease [Member]	Jun. 30, 2012 Single Issuer Corporate Debt Security [Member]
Available-for-sale Securities, Gross Unrealized Losses	$ 1,700
Available-for-sale Securities, Change in Net Unrealized Holding Gain (Loss) before Taxes	95		(611)	35
Percent Change Unrealized Loss Investment Securities					2.30%	68.60%	5.20%
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	1,500
Available-for-sale Securities, Amortized Cost Basis	$ 601,810	$ 583,951						$ 4,300