Note 4 - Investment Securities (Detail) - Investment Portfolio Gross Unrealized Losses and Fair Value (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Residential Mortgage Backed Securities [Member]
Securities available-for-sale:
Securities available-for-sale unrealized loss less than 12 months fair value	$ 28,112	$ 40,041
Securities available-for-sale unrealized loss less than 12 months unrealized losses	(230)	(567)
Securities available-for-sale unrealized loss 12 months or more fair value	0	0
Securities available-for-sale unrealized loss 12 months or more unrealized losses	0	0
Securities available-for-sale unrealized loss fair value	28,112	40,041
Securities available-for-sale unrealized loss unrealized losses	(230)	(567)
Commercial Mortgage Backed Securities [Member]
Securities available-for-sale:
Securities available-for-sale unrealized loss less than 12 months fair value	37,538
Securities available-for-sale unrealized loss less than 12 months unrealized losses	(710)
Securities available-for-sale unrealized loss 12 months or more fair value	0
Securities available-for-sale unrealized loss 12 months or more unrealized losses	0
Securities available-for-sale unrealized loss fair value	37,538
Securities available-for-sale unrealized loss unrealized losses	(710)
All Other Debt Securities [Member]
Securities available-for-sale:
Securities available-for-sale unrealized loss less than 12 months fair value	56,880	30,931
Securities available-for-sale unrealized loss less than 12 months unrealized losses	(301)	(224)
Securities available-for-sale unrealized loss 12 months or more fair value	415	415
Securities available-for-sale unrealized loss 12 months or more unrealized losses	(85)	(85)
Securities available-for-sale unrealized loss fair value	57,295	31,346
Securities available-for-sale unrealized loss unrealized losses	(386)	(309)
Total [Member]
Securities available-for-sale:
Securities available-for-sale unrealized loss less than 12 months fair value	122,530	70,972
Securities available-for-sale unrealized loss less than 12 months unrealized losses	(1,241)	(791)
Securities available-for-sale unrealized loss 12 months or more fair value	415	415
Securities available-for-sale unrealized loss 12 months or more unrealized losses	(85)	(85)
Securities available-for-sale unrealized loss fair value	122,945	71,387
Securities available-for-sale unrealized loss unrealized losses	$ (1,326)	$ (876)