Note 2 - Acquisition (Detail) - Bargain Purchase Gain on Acquisition (USD $) In Thousands, unless otherwise specified	0 Months Ended	12 Months Ended
	Aug. 20, 2010	Dec. 31, 2010
Sonoma Valley Bank tangible shareholder's equity	$ 13,923
Adjustments to reflect assets acquired and liabilities assumed at fair value:
Gain on acquisition	178	178
Cash Payment From FDIC [Member]
Adjustments to reflect assets acquired and liabilities assumed at fair value:
Adjustment	21,270
Loans And Leases Net [Member]
Adjustments to reflect assets acquired and liabilities assumed at fair value:
Adjustment	(34,562)
Other Real Estate Owned [Member]
Adjustments to reflect assets acquired and liabilities assumed at fair value:
Adjustment	(1,491)
Other Assets [Member]
Adjustments to reflect assets acquired and liabilities assumed at fair value:
Adjustment	(811)
Core Deposits [Member]
Adjustments to reflect assets acquired and liabilities assumed at fair value:
Adjustment	5,270
Deposits [Member]
Adjustments to reflect assets acquired and liabilities assumed at fair value:
Adjustment	(1,233)
Federal Home Loan Bank Advances [Member]
Adjustments to reflect assets acquired and liabilities assumed at fair value:
Adjustment	(1,872)
Other Liabilities [Member]
Adjustments to reflect assets acquired and liabilities assumed at fair value:
Adjustment	$ (316)