DIVIDEND AVAILABILITY AND REGULATORY MATTERS (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
DIVIDEND AVAILABILITY AND REGULATORY MATTERS
Period of net earnings considered in declaring dividend without the approval of the DFI	3 years
Dividends received from the Bank	$ 50,000,000
Tier I capital (to average assets):
Actual, Amount	570,082,000	566,908,000
Actual, Ratio (as a percent)	10.53%	10.42%
Well Capitalized Minimum Requirement, Amount	270,694,000	272,142,000
Well Capitalized Minimum Requirement, Ratio (as a percent)	5.00%	5.00%
Excess Capital Amount	299,388,000	294,766,000
Tier I capital (to risk-weighted assets):
Actual, Amount	570,082,000	566,908,000
Ratio (as a percent)	15.17%	15.97%
Well Capitalized Minimum Requirement, Amount	225,541,000	213,022,000
Well Capitalized Minimum Requirement, Ratio (as a percent)	6.00%	6.00%
Excess Capital Amount	344,541,000	353,886,000
Total capital (to risk-weighted assets):
Actual, Amount	617,702,000	612,284,000
Actual, Ratio (as a percent)	16.43%	17.25%
Well Capitalized Minimum Requirement, Amount	375,901,000	355,037,000
Well Capitalized Minimum Requirement, Ratio (as a percent)	10.00%	10.00%
Excess Capital Amount	241,801,000	257,247,000
Trust preferred securities included in tier 1 capital
Trust preferred securities issued	105,000,000
Amount of trust preferred securities included in tier 1 capital	105,000,000
Maturity period of trust preferred securities included in Tier I capital	10 years
Number of months for which cumulative net earnings are not sufficient for dividend payments due for those periods, requiring prior notification to FRB	12 months
Minimum
Tier I capital (to average assets):
Actual, Ratio (as a percent)	4.00%
Well Capitalized Minimum Requirement, Ratio (as a percent)	5.00%
Tier I capital (to risk-weighted assets):
Ratio (as a percent)	4.00%
Well Capitalized Minimum Requirement, Ratio (as a percent)	6.00%
Total capital (to risk-weighted assets):
Actual, Ratio (as a percent)	8.00%
Well Capitalized Minimum Requirement, Ratio (as a percent)	10.00%
Maximum
Trust preferred securities included in tier 1 capital
Trust preferred securities included in tier 1 capital, expressed as a percentage of the sum of all core capital elements	25.00%
Pacific Western Bank
Tier I capital (to average assets):
Actual, Amount	528,151,000	528,782,000
Actual, Ratio (as a percent)	9.78%	9.73%
Well Capitalized Minimum Requirement, Amount	269,901,000	271,721,000
Well Capitalized Minimum Requirement, Ratio (as a percent)	5.00%	5.00%
Excess Capital Amount	258,250,000	257,061,000
Tier I capital (to risk-weighted assets):
Actual, Amount	528,151,000	528,782,000
Ratio (as a percent)	14.10%	14.95%
Well Capitalized Minimum Requirement, Amount	224,778,000	212,269,000
Well Capitalized Minimum Requirement, Ratio (as a percent)	6.00%	6.00%
Excess Capital Amount	303,373,000	316,513,000
Total capital (to risk-weighted assets):
Actual, Amount	575,614,000	574,003,000
Actual, Ratio (as a percent)	15.36%	16.22%
Well Capitalized Minimum Requirement, Amount	374,630,000	353,781,000
Well Capitalized Minimum Requirement, Ratio (as a percent)	10.00%	10.00%
Excess Capital Amount	$ 200,984,000	$ 220,222,000