COVERED ASSETS AND FDIC INDEMNIFICATION ASSET (Details 3) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Allowance for loan losses disclosures
Allowance on covered loans	$ 10,110,000		$ 5,153,000
Percentage of allowance allocated to covered loans	4.20%
Provision for covered loans	5,089,000	1,621,000
United Commercial Bank (UCB)
Allowance for loan losses disclosures
Period before which the acquisition was made	3 years 6 months
Washington First International Bank (WFIB)
Allowance for loan losses disclosures
Period before which the acquisition was made	3 years
Covered loans accounted for under ASC 310-30
Allowance for loan losses disclosures
Provision for covered loans	2,000,000
Covered loans accounted for under ASC 310-30 | Commercial Real Estate ("CRE")
Allowance for loan losses disclosures
Allowance on covered loans	2,000,000
Specific covered loans outside of the scope of ASC 310-30
Allowance for loan losses disclosures
Allowance allocated to additional advances	8,100,000		5,200,000
Percentage of allowance allocated to covered loans	3.40%		2.20%
Provision for covered loans	3,100,000		1,600,000
Additional advances under shared-loss agreements	408,900,000		431,700,000
Charge-offs		0
Specific covered loans outside of the scope of ASC 310-30 | Commercial and Industrial ("C&I")
Allowance for loan losses disclosures
Allowance allocated to additional advances	4,800,000		2,400,000
Additional advances under shared-loss agreements	284,100,000		302,300,000
Charge-offs	132,000
Specific covered loans outside of the scope of ASC 310-30 | Commercial Real Estate ("CRE")
Allowance for loan losses disclosures
Allowance allocated to additional advances	2,800,000		2,500,000
Additional advances under shared-loss agreements	81,200,000		83,400,000
Specific covered loans outside of the scope of ASC 310-30 | Consumer
Allowance for loan losses disclosures
Allowance allocated to additional advances	407,000		194,000
Additional advances under shared-loss agreements	33,000,000		34,500,000
Specific covered loans outside of the scope of ASC 310-30 | Residential
Allowance for loan losses disclosures
Allowance allocated to additional advances	160,000		87,000
Additional advances under shared-loss agreements	$ 10,600,000		$ 11,500,000