Stockholders' Equity - Narrative (Details) - USD ($)		3 Months Ended
	Nov. 30, 2023	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2026	Dec. 31, 2025	Apr. 23, 2025	Mar. 17, 2025	Jun. 06, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock Amortization		$ 5,900,000	$ 5,200,000
Vesting period of time-based restricted stock, lower limit		3 years
Preferred stock issued (shares)		513,250
Preferred Stock, Shares Authorized	50,000,000
Common stock, outstanding (in shares)		153,722,123			149,963,520
Common stock, issued (in shares)		153,784,724			150,039,018
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		$ 24.60
Term of warrants		7 years
Common shares purchased under Dividend Reinvestment Plan		$ 12,080,000
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of time-based restricted stock, higher limit		4 years
Stock Repurchase Plan - March 17, 2025
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Repurchase Program, Authorized, Amount							$ 150,000,000.0
Stock Repurchase Plan - April 23, 2025
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Repurchase Program, Authorized, Amount						$ 300,000,000.0
Stock Repurchase Plan - March 23, 2026
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchased (in shares)		1,709,935
Stock repurchased (in dollars per share)		$ 18.68
Common shares purchased under Dividend Reinvestment Plan		$ 31,900,000
Share Repurchase Program, Remaining Authorized, Amount		$ 82,600,000
Centerbridge Investor
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Warrants Issued, Per Share Price	$ 15.375
BANC
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, outstanding (in shares)		149,963,520			153,722,123
Common Stock, Shares Authorized		446,863,844			446,863,844
Preferred Class A | Pacific Western Bank
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Investment Interest Rate								7.75%
NVCE Non-voting Share Class
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred Stock, Shares Authorized		27,000,000			27,000,000
Common stock, outstanding (in shares)				5,017,064
NVCE Non-voting Share Class | Centerbridge Investor
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, issued (in shares)	3,048,780
NVCE Non-voting Share Class | Warburg Investors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, issued (in shares)	15,853,659
Class B Nonvoting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, outstanding (in shares)		477,321
Common Stock, Shares Authorized		3,136,156
Common stock, issued (in shares)		477,321			477,321
Nonvoting Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, issued (in shares)		0			5,017,064
Nonvoting Common Stock Equivalents
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Conversion of non-voting common stock equivalents to Voting Common Stock		(1,000,000)
Sale of Stock, Price Per Share		$ 20
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted shares (shares)		2,505,680
PacWest 2018 Amended and Revised Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (shares)		10,717,882
Number of shares available for grant (shares)		2,157,723
Unrecognized share based compensation expense		$ 63,800,000
PacWest 2018 Amended and Revised Stock Incentive Plan | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted shares (shares)		3,026,160
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)		62,601