ACQUISITIONS (Details 2) (USD $)	3 Months Ended			6 Months Ended		0 Months Ended	3 Months Ended
	Jun. 30, 2013 item	Mar. 31, 2013	Jun. 30, 2012	Jun. 30, 2013 item	Jun. 30, 2012	May 31, 2013 First California Financial Group item	Jun. 30, 2013 First California Financial Group	Aug. 01, 2012 American Perspective	Aug. 01, 2012 American Perspective Pacific Western Bank item	Apr. 03, 2012 Celtic	Apr. 03, 2012 Celtic Pacific Western Bank Maximum
Acquisition
Number of shares of entity receivable by stockholders of acquiree for each share of acquiree						0.2966
Measuring period for determining weighted average price per share for fluctuating shares						20 days
Issuance of common stock (in shares)						8,400,000
Common stock of acquiree cancelled in merger						1,000,000
Closing stock price (in dollars per share)						$ 28.83
Total consideration paid						$ 246,346,000		$ 58,076,000		$ 18,000,000
Number of operating branches						15
Number of operating branches which overlapped with existing branches						8
Number of operating branches closed as part of the integration and system conversion						6
Number of operating branches closed in consolidation						2
Number of operating branches added to its branch system as a result of branch conversion and closure activity						7
Revenue	203,000	2,840,000	4,871,000	3,043,000	8,133,000		4,700,000
Noninterest expense	64,216,000	44,183,000	47,585,000	108,399,000	116,480,000		2,300,000
Net earnings	4,349,000	13,494,000	15,557,000	17,843,000	20,821,000		1,400,000
Goodwill						129,517,000		15,047,000		6,645,000
Loan market considered in granting loan											$ 5,000,000
Number of branches	75			75					2