Dividend Availability and Regulatory Matters Dividend Availability and Regulatory Matters (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%
Banking Regulation, Common Equity Tier 1 Risk-Based Capital Ratio, Well Capitalized, Minimum	6.50%
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	8.00%
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%
Bank of California, inc.
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier One Leverage Capital	$ 3,402,044,000	$ 3,503,201,000
Tier One Leverage Capital to Average Assets	9.00%	8.61%
Tier One Leverage Capital Required to be Well Capitalized	$ 1,889,775,000	$ 2,033,411,000
Tier One Leverage Capital Required to be Well Capitalized to Average Assets		5.00%
Tier One Risk Based Common Equity	$ 2,772,528,000	$ 2,873,685,000
Common Equity Tier One Capital Ratio	10.14%	8.70%
Tier One Risk Based Common Equity Required to be Well Capitalized	$ 1,777,025,000	$ 2,147,012,000
Banking Regulation, Common Equity Tier 1 Risk-Based Capital Ratio, Well Capitalized, Minimum		6.50%
Banking Regulation, Capital Conservation Buffer, Common Equity Tier 1 Risk-Based Capital, Actual		7.00%
Tier One Risk Based Capital	$ 3,402,044,000	$ 3,503,201,000
Tier One Risk Based Capital to Risk Weighted Assets	12.44%	10.61%
Tier One Risk Based Capital Required to be Well Capitalized	$ 2,187,108,000	$ 2,642,477,000
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets		8.00%
Banking Regulation, Capital Conservation Buffer, Tier 1 Risk-Based Capital, Actual		8.50%
Capital	$ 4,490,493,000	$ 4,495,750,000
Capital to Risk Weighted Assets	16.43%	13.61%
Capital Required to be Well Capitalized	$ 2,733,885,000	$ 3,303,096,000
Capital Required to be Well Capitalized to Risk Weighted Assets		10.00%
Banking Regulation, Capital Conservation Buffer, Total Risk-Based Capital, Actual		10.50%
Bank of California
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier One Leverage Capital	$ 3,617,643,000	$ 3,408,289,000
Tier One Leverage Capital to Average Assets	9.62%	8.39%
Tier One Leverage Capital Required to be Well Capitalized	$ 1,880,850,000	$ 2,031,413,000
Tier One Leverage Capital Required to be Well Capitalized to Average Assets		5.00%
Tier One Risk Based Common Equity	$ 3,617,643,000	$ 3,408,289,000
Common Equity Tier One Capital Ratio	13.27%	10.32%
Tier One Risk Based Common Equity Required to be Well Capitalized	$ 1,772,549,000	$ 2,145,738,000
Banking Regulation, Common Equity Tier 1 Risk-Based Capital Ratio, Well Capitalized, Minimum		6.50%
Banking Regulation, Capital Conservation Buffer, Common Equity Tier 1 Risk-Based Capital, Actual		7.00%
Tier One Risk Based Capital	$ 3,617,643,000	$ 3,408,289,000
Tier One Risk Based Capital to Risk Weighted Assets	13.27%	10.32%
Tier One Risk Based Capital Required to be Well Capitalized	$ 2,181,599,000	$ 2,640,909,000
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets		8.00%
Banking Regulation, Capital Conservation Buffer, Tier 1 Risk-Based Capital, Actual		8.50%
Capital	$ 4,295,821,000	$ 4,074,047,000
Capital to Risk Weighted Assets	15.75%	12.34%
Capital Required to be Well Capitalized	$ 2,726,998,000	$ 3,301,136,000
Capital Required to be Well Capitalized to Risk Weighted Assets		10.00%
Banking Regulation, Capital Conservation Buffer, Total Risk-Based Capital, Actual		10.50%