Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	Apr. 30, 2019
Document and Entity Information [Abstract]
Entity Registrant Name	PACWEST BANCORP
Entity Central Index Key	0001102112
Document Period End Date	Mar. 31, 2019
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		118,833,032