Acquisitions Acquisitions (Details) (USD $) In Thousands, unless otherwise specified	0 Months Ended	1 Months Ended
	Apr. 07, 2014	May 31, 2013	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013
Business Acquisition [Line Items]
Cash and due from banks	$ 768,553	$ 6,124
Interest-earning deposits in financial institutions	60,612	266,889
Investments securities available-for-sale	382,797	4,444
FHLB stock	46,060	9,518
Loans and leases	6,877,427	1,049,613
Equipment leased to others under operating leases	160,015	0	125,119	0
Premises and equipment	12,663	15,322
Foreclosed Assets	6,382	13,772
FDIC loss sharing asset	0	17,241
Income Tax Assets	311,462	33,360
Goodwill	1,520,031	129,070	1,722,129	208,743	215,862
Other intangible assets	6,720	7,927
Other assets	581,905	27,576
Total assets acquired	10,734,627	1,580,856
Noninterest-bearing deposits	4,631	361,166
Interest-bearing deposits	6,236,419	739,713
Other borrowings	992,109	0
Subordinated Debentures	300,918	24,061
Discontinued operations	0	184,619
Accrued interest payable and other liabilities	123,362	19,729
Total liabilities assumed	7,657,439	1,329,288
Total consideration paid	3,077,188	251,568
Cash paid	483,118	0
PacWest common stock issued	2,594,070	242,268
Cancellation of FCAL common stock owned by PacWest (at acquisition date fair value)	0	9,300
First California Financial Group, Inc. [Domain]
Business Acquisition [Line Items]
Total consideration paid		251,568
Capitalsource, Inc. [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Apr. 07, 2014
Total consideration paid	$ 3,077,188