ACQUISITIONS (Details) (USD $) In Thousands, unless otherwise specified				0 Months Ended			0 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	May 31, 2013 First California Financial Group	Aug. 03, 2012 American Perspective Bank	Aug. 01, 2012 American Perspective Bank	Apr. 03, 2012 Celtic Capital Corporation	Jan. 03, 2012 Pacific Western Equipment Finance
Assets Acquired:
Cash and due from banks				$ 6,124		$ 3,370	$ 3,435	$ 7,092
Interest-earning deposits in financial institutions				266,889		10,081
Investment securities available-for-sale				4,444		48,887
FHLB stock				9,518		1,412
Loans and leases				1,049,613		197,279	54,963	140,959
Other real estate owned				13,772		1,561
Premises and equipment				15,322
FDIC loss sharing asset				17,241
Cash surrender value of life insurance				13,265
Goodwill	215,862	79,866	79,592	136,189		15,047	6,645	19,033
Core deposit and customer relationship intangibles				7,927		1,924	1,300	1,700
Other intangible assets							670	1,420
Leases in process								19,162
Other assets				40,192		4,234	69	467
Total assets acquired				1,580,496		283,795	67,082	189,833
Liabilities Assumed:
Noninterest-bearing deposits				361,166		40,673
Interest-bearing deposits				739,713		178,891
Borrowings from parent								128,677
Other borrowings						5,315	46,804	15,839
Subordinated debentures				24,061
Discontinued operations				184,619
Accrued interest payable and other liabilities				19,369		840	2,278	10,317
Total liabilities assumed				1,328,928		225,719	49,082	154,833
Total consideration paid				251,568	58,076		18,000	35,000
Summary of consideration:
Cash paid					58,076		18,000	35,000
PacWest common stock issued				242,268
Cancellation of FCAL common stock owned by PacWest				9,300
Total consideration paid				$ 251,568	$ 58,076		$ 18,000	$ 35,000