Loans - Narrative (Details) $ in Thousands	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2024 USD ($) loan	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Purchased with Credit Deterioration, Discount (Premium)	$ 9,200			$ 9,600
Federal Home Loan Bank, Advances, General Debt Obligations, Maximum Amount Available	5,500,000	$ 5,500,000		4,800,000
Proceeds from sale of SBA loans	0	23,100	$ 8,800
Gain on sale of SBA loans		1,415	501
Consumer mortgage loans secured by residential real estate in process of foreclosure	0	0		1,000
Financing receivable, allowance for credit loss	139,464	139,464		134,771
Allowance for credit loss adjustment	42,200	42,200
Nonperforming loan balances, excluding government guaranteed balances	$ 12,900	12,900		10,700
Number of loans that experienced default | loan	0
Other Assets
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accrued interest receivable	$ 70,100	70,100		66,700
Enterprise Value Lending Portfolio Niche Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for credit loss adjustment	12,600	12,600
Commercial and industrial | Term Extension
Accounts, Notes, Loans and Financing Receivable [Line Items]
Default subsequent to term extension			700
Non-Covered Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, allowance for credit loss	139,464	139,464	141,319	134,771	$ 135,498	$ 138,295	$ 136,932
Non-Covered Loans | Enterprise Value Lending Portfolio Niche Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, allowance for credit loss	19,900	19,900		23,000
Non-Covered Loans | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, allowance for credit loss	61,478	61,478	$ 60,318	$ 58,886	$ 58,714	$ 59,149	$ 53,835
Cumulative Effect, Period Of Adoption, Adjustment | Non-Covered Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, allowance for credit loss	$ 14,600	$ 14,600
Cumulative Effect, Period Of Adoption, Adjustment | Non-Covered Loans | Baseline
Accounts, Notes, Loans and Financing Receivable [Line Items]
Growth upside forecast	0.40	0.40
Cumulative Effect, Period Of Adoption, Adjustment | Non-Covered Loans | Near-term growth upside
Accounts, Notes, Loans and Financing Receivable [Line Items]
Growth upside forecast	0.30	0.30
Cumulative Effect, Period Of Adoption, Adjustment | Non-Covered Loans | Moderate recession downside
Accounts, Notes, Loans and Financing Receivable [Line Items]
Growth upside forecast	0.30	0.30
Cumulative Effect, Period Of Adoption, Adjustment | Non-Covered Loans | Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Federal funds forecast	0.0525	0.0525
Cumulative Effect, Period Of Adoption, Adjustment | Non-Covered Loans | Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Federal funds forecast	0.0550	0.0550