Fair Value Measurements - Estimated Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Financial assets:
Held to maturity securities	$ 649,872	$ 731,858
Loans held for investment, net	7,849,435	7,968,332
Broker-dealer and clearing organization receivables	1,452,366	1,573,931
Financial liabilities:
Broker-dealer and clearing organization payables	1,331,902	1,430,734
Carrying Value
Financial assets:
Cash and cash equivalents	2,299,627	1,859,350
Assets segregated for regulatory purposes	70,963	57,395
Securities purchased under agreements to resell	88,728	80,011
Held to maturity securities	737,899	812,677
Loans held for sale	48,883	121,652
Loans held for investment, net	7,849,435	7,957,474
Broker-dealer and clearing organization receivables	1,452,366	1,573,931
Other assets	69,545	74,613
Financial liabilities:
Deposits	11,065,322	11,063,192
Broker-dealer and clearing organization payables	1,331,902	1,430,734
Short-term borrowings	834,023	900,038
Debt	347,667	347,145
Other liabilities	16,779	24,280
Fair Value
Financial assets:
Cash and cash equivalents	2,299,627	1,859,350
Assets segregated for regulatory purposes	70,963	57,395
Securities purchased under agreements to resell	88,728	80,011
Held to maturity securities	649,872	731,858
Loans held for sale	50,871	122,240
Loans held for investment, net	7,936,567	8,040,565
Broker-dealer and clearing organization receivables	1,452,366	1,573,931
Other assets	69,545	74,613
Financial liabilities:
Deposits	11,058,234	11,045,957
Broker-dealer and clearing organization payables	1,331,902	1,430,734
Short-term borrowings	834,023	900,038
Debt	331,965	319,505
Other liabilities	16,779	24,280
Fair Value \| Level 1
Financial assets:
Cash and cash equivalents	2,299,627	1,859,350
Assets segregated for regulatory purposes	70,963	57,395
Fair Value \| Level 2
Financial assets:
Securities purchased under agreements to resell	88,728	80,011
Held to maturity securities	649,872	731,858
Loans held for sale	1,436	99,358
Loans held for investment, net	363,718	344,172
Broker-dealer and clearing organization receivables	1,452,366	1,573,931
Other assets	69,545	74,613
Financial liabilities:
Deposits	11,058,234	11,045,957
Broker-dealer and clearing organization payables	1,331,902	1,430,734
Short-term borrowings	834,023	900,038
Debt	331,965	319,505
Other liabilities	16,779	24,280
Fair Value \| Level 3
Financial assets:
Loans held for sale	49,435	22,882
Loans held for investment, net	$ 7,572,849	$ 7,696,393

Fair value portion of assets segregated for regulatory purposes.

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Amount payable to other broker-dealer and clearing organization, including, but not limited to, security failed-to-receive, deposit received for security loaned, open transaction, and floor-brokerage payable.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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Fair value portion of federal funds sold and securities borrowed or purchased under agreements to resell.

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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Amortized cost, after allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement and net investment in lease.

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Fair value portion of other assets.

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Amount receivable from broker-dealers and clearing organizations, including, but not limited to, securities failed-to-deliver, certain deposits for securities borrowed, open transactions, good faith and margin deposits, commissions and floor brokerage receivables.

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