Cover Page - shares	9 Months Ended
	Sep. 30, 2019	Oct. 30, 2019
Cover page.
Title of 12(b) Security	Common Stock, par value $0.01 per share
Entity Address, City or Town	Beverly Hills
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	90212
City Area Code	310
Local Phone Number	887-8500
Entity Current Reporting Status	Yes
Trading Symbol	PACW
Entity Incorporation, State or Country Code	DE
Entity Registrant Name	PACWEST BANCORP
Entity Address, Address Line One	9701 Wilshire Blvd., Suite 700
Entity Central Index Key	0001102112
Document Period End Date	Sep. 30, 2019
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Entity File Number	001-36408
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		118,212,594
Entity Tax Identification Number	33-0885320
Security Exchange Name	NASDAQ
Entity Interactive Data Current	Yes
Entity Shell Company	false
Document Quarterly Report	true
Document Transition Report	false
Entity Small Business	false
Entity Emerging Growth Company	false