Note 10 - Risk-Based Capital (Tables)

12 Months Ended

Dec. 31, 2012

Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block]

						For Capital Adequacy Purposes					To Be Well Capitalized Under the FDICIA Prompt Corrective Action Provisions
At December 31, 2012	Amount		Ratio			Amount		Ratio			Amount		Ratio
	(Dollars in thousands)
Total Capital (to risk-weighted assets)
Consolidated Company	$	444,205		16.33	%	$	217,627		8.00	%	$	272,033		10.00	%
Westamerica Bank		418,746		15.62	%		214,452		8.00	%		268,065		10.00	%
Tier 1 Capital (to risk-weighted assets)
Consolidated Company		409,763		15.06	%		108,813		4.00	%		163,220		6.00	%
Westamerica Bank		378,921		14.14	%		107,226		4.00	%		160,839		6.00	%
Leverage Ratio *
Consolidated Company		409,763		8.56	%		191,396		4.00	%		239,245		5.00	%
Westamerica Bank		378,921		7.99	%		189,788		4.00	%		237,236		5.00	%

						For Capital Adequacy Purposes					To Be Well Capitalized Under the FDICIA Prompt Corrective Action Provisions
At December 31, 2011	Amount		Ratio			Amount		Ratio			Amount		Ratio
	(Dollars in thousands)
Total Capital (to risk-weighted assets)
Consolidated Company	$	444,659		15.83	%	$	224,664		8.00	%	$	280,830		10.00	%
Westamerica Bank		424,446		15.32	%		221,578		8.00	%		276,973		10.00	%
Tier 1 Capital (to risk-weighted assets)
Consolidated Company		408,266		14.54	%		112,332		4.00	%		168,498		6.00	%
Westamerica Bank		383,375		13.84	%		110,789		4.00	%		166,184		6.00	%
Leverage Ratio *
Consolidated Company		408,266		8.38	%		194,969		4.00	%		243,711		5.00	%
Westamerica Bank		383,375		7.93	%		193,406		4.00	%		241,757		5.00	%