Dividend Availability and Regulatory Matters Dividend Availability and Regulatory Matters (Details) $ in Thousands	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier One Leverage Capital	$ 3,503,201	$ 2,657,575
Tier One Leverage Capital Required to be Well Capitalized	2,033,411	$ 1,942,017
Tier One Leverage Capital Required to be Well Capitalized to Average Assets		0.0500
Tier One Risk Based Common Equity	2,873,685	$ 2,526,575
Tier One Risk Based Common Equity Required to be Well Capitalized	2,147,012	$ 1,853,073
Tier One Risk Based Common Equity Required to be Well Capitalized to Risk Weighted Assets		6.50%
Tier One Risk Based Capital	3,503,201	$ 2,657,575
Tier One Risk Based Capital Required to be Well Capitalized	2,642,477	$ 2,280,705
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets		0.0800
Capital	4,495,750	$ 3,619,190
Capital Required to be Well Capitalized	3,303,096	$ 2,850,881
Capital Required to be Well Capitalized to Risk Weighted Assets		0.1000
Pacific Western Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier One Leverage Capital	3,408,289	$ 2,717,374
Tier One Leverage Capital Required to be Well Capitalized	2,031,413	$ 1,940,510
Tier One Leverage Capital Required to be Well Capitalized to Average Assets		0.0500
Tier One Risk Based Common Equity	3,408,289	$ 2,717,374
Tier One Risk Based Common Equity Required to be Well Capitalized	2,145,738	$ 1,847,853
Tier One Risk Based Common Equity Required to be Well Capitalized to Risk Weighted Assets		6.50%
Tier One Risk Based Capital	3,408,289	$ 2,717,374
Tier One Risk Based Capital Required to be Well Capitalized	2,640,909	$ 2,274,281
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets		0.0800
Capital	4,074,047	$ 3,355,403
Capital Required to be Well Capitalized	$ 3,301,136	$ 2,842,851
Capital Required to be Well Capitalized to Risk Weighted Assets		0.1000