Stockholders' Equity - Narrative (Details)	3 Months Ended		6 Months Ended
Stockholders' Equity - Narrative (Details)	Jun. 30, 2023 USD ($) $ / shares shares	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) $ / shares shares	Dec. 31, 2022 $ / shares shares	Jun. 06, 2022 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock Amortization \| $	$ 7,700,000	$ 9,000,000
Unvested restricted shares (shares)	1,626,235		1,626,235	2,405,878
Vesting period of time-based restricted stock, lower limit			3 years
Preferred stock issued (shares)	513,250		513,250	513,250	20,530,000
Preferred Stock, Liquidation Preference Per Share \| $ / shares	$ 1,000		$ 1,000	$ 1,000	$ 1,000
Preferred Stock Depository Share \| $	$ 25.00		$ 25.00
Preferred stock par value (usd per share) \| $ / shares	$ 0.01		$ 0.01	$ 0.01
1/40th Ownership Interest					0.025
Preferred Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Investment Interest Rate					7.75%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of time-based restricted stock, higher limit			4 years
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted shares (shares)	656,049		656,049
Vesting term			3 years
Performance Shares \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			0.00%
Performance Shares, Two \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			200.00%
PacWest 2017 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant (shares)	1,869,341		1,869,341
Unrecognized share based compensation expense \| $	$ 55,300,000		$ 55,300,000
PacWest 2017 Stock Incentive Plan [Member] \| Time-Based Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted shares (shares)	1,626,235		1,626,235
PacWest 2017 Revised Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (shares)	6,650,000		6,650,000

PACWEST BANCORP 10-Q