Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 31, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	PACWEST BANCORP
Entity Central Index Key	0001102112
Document Period End Date	Jun. 30, 2018
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		122,429,348