Fair Value of Financial Instruments and Other Assets - Financial Instruments Not Measured at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Assets
Receivable from brokers and dealers and clearing organizations	$ 135,760	$ 67,805
Deposits with clearing organizations	102,048	54,702
Accounts receivable	271,505	222,268
Total assets measured at fair value	1,103,887	1,136,183
Liabilities
Payable to brokers and dealers and clearing organizations	104,799	67,816
Fair Value, Nonrecurring
Assets
Cash and restricted cash	222,570	224,169
Receivable from brokers and dealers and clearing organizations	135,760	67,805
Deposits with clearing organizations	102,048	54,702
Accounts receivable	271,505	222,268
Other assets – Memberships in clearing organizations	3,126	2,918
Total assets measured at fair value	735,009	571,862
Liabilities
Payable to brokers and dealers and clearing organizations	104,799	67,816
Total	104,799	67,816
Total Fair Value \| Fair Value, Nonrecurring
Assets
Cash and restricted cash	222,570	224,169
Receivable from brokers and dealers and clearing organizations	135,760	67,805
Deposits with clearing organizations	102,048	54,702
Accounts receivable	271,505	222,268
Other assets – Memberships in clearing organizations	3,126	2,918
Total assets measured at fair value	735,009	571,862
Liabilities
Payable to brokers and dealers and clearing organizations	104,799	67,816
Total	104,799	67,816
Quoted Prices in active Markets for Identical Assets (Level 1)
Assets
Total assets measured at fair value	1,084,885	1,117,133
Quoted Prices in active Markets for Identical Assets (Level 1) \| Fair Value, Nonrecurring
Assets
Cash and restricted cash	222,570	224,169
Receivable from brokers and dealers and clearing organizations	0	0
Deposits with clearing organizations	102,048	54,702
Accounts receivable	0	0
Other assets – Memberships in clearing organizations	0	0
Total assets measured at fair value	324,618	278,871
Liabilities
Payable to brokers and dealers and clearing organizations	0	0
Total	0	0
Significant Observable Inputs (Level 2)
Assets
Total assets measured at fair value	0	7,844
Significant Observable Inputs (Level 2) \| Fair Value, Nonrecurring
Assets
Cash and restricted cash	0	0
Receivable from brokers and dealers and clearing organizations	135,760	67,805
Deposits with clearing organizations	0	0
Accounts receivable	271,505	222,268
Other assets – Memberships in clearing organizations	0	0
Total assets measured at fair value	407,265	290,073
Liabilities
Payable to brokers and dealers and clearing organizations	104,799	67,816
Total	104,799	67,816
Significant Unobservable Inputs (Level 3)
Assets
Total assets measured at fair value	19,002	11,206
Significant Unobservable Inputs (Level 3) \| Fair Value, Nonrecurring
Assets
Cash and restricted cash	0	0
Receivable from brokers and dealers and clearing organizations	0	0
Deposits with clearing organizations	0	0
Accounts receivable	0	0
Other assets – Memberships in clearing organizations	3,126	2,918
Total assets measured at fair value	3,126	2,918
Liabilities
Payable to brokers and dealers and clearing organizations	0	0
Total	$ 0	$ 0

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.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Rule 15c3-1
-Number 240
-Section 15c3-1
-Publisher SEC

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 940
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481833/940-20-45-3

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Account receivable excluding receivable from brokers and dealers and clearing organizations, net of allowance.

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Fair value portion of asset recognized for present right to economic benefit.

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Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 100
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Fair value of financial and nonfinancial obligations.

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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.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-Name Accounting Standards Codification
-Section 45
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481833/940-20-45-3

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Amount of right to receive cash and securities on deposit with clearing organizations. Clearing organizations perform post trade processing and trade comparisons among numerous broker-dealers and act as settlement agents between buying and selling broker-dealers.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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