Acquisitions Acquisitions (Details) (USD $)	0 Months Ended	1 Months Ended
	Apr. 07, 2014	May 31, 2013	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013
Business Acquisition [Line Items]
Cash and due from banks	$ 768,553,000	$ 6,124,000
Interest-earning deposits in financial institutions	60,612,000	266,889,000
Investments securities available-for-sale	383,723,000	4,444,000
FHLB stock	46,060,000	9,518,000
Loans and leases	6,886,035,000	1,049,613,000
Equipment Leased To Others Under Operating Leases	160,015,000	0	127,289,000	0
Premises and equipment	12,663,000	15,322,000
Foreclosed Assets	6,382,000	13,772,000
FDIC loss sharing asset	0	17,241,000
Income Tax Assets	300,310,000	33,360,000
Goodwill	1,523,055,000	129,070,000	1,725,153,000	208,743,000	209,190,000
Other intangible assets	6,720,000	7,927,000
Other assets	580,499,000	27,576,000
Total assets acquired	10,734,627,000	1,580,856,000
Noninterest-bearing deposits	4,631,000	361,166,000
Interest-bearing deposits	6,236,419,000	739,713,000
Other borrowings	992,109,000	0
Subordinated Debentures	300,918,000	24,061,000
Discontinued operations	0	184,619,000
Accrued interest payable and other liabilities	123,362,000	19,729,000
Total liabilities assumed	7,657,439,000	1,329,288,000
Total consideration paid	3,077,188,000	251,568,000
Cash paid	483,118,000	0
PacWest common stock issued	2,594,070,000	242,268,000
Cancellation of FCAL common stock owned by PacWest (at acquisition date fair value)	0	9,300,000
First California Financial Group, Inc. [Domain]
Business Acquisition [Line Items]
Total consideration paid		251,568,000
Cancellation of FCAL common stock owned by PacWest (at acquisition date fair value)		$ 4,100,000