Fair Value of Financial Instruments and Other Assets - Financial Instruments Not Measured at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Assets
Receivable from brokers and dealers and clearing organizations	$ 131,252	$ 8,630
Deposits with clearing organizations	57,346	58,282
Accounts receivable	351,009	257,845
Total assets measured at fair value	2,021,977	2,102,557
Liabilities
Payable to brokers and dealers and clearing organizations	130,651	3,363
Total		6,657
Fair Value, Nonrecurring
Assets
Cash and restricted cash	215,464	275,179
Receivable from brokers and dealers and clearing organizations	131,252	8,630
Deposits with clearing organizations	57,346	58,282
Accounts receivable	351,009	257,845
Other assets – Memberships in clearing organizations	3,268	3,127
Total assets measured at fair value	758,339	603,063
Liabilities
Payable to brokers and dealers and clearing organizations	130,651	3,363
Total	130,651	3,363
Total Fair Value \| Fair Value, Nonrecurring
Assets
Cash and restricted cash	215,464	275,179
Receivable from brokers and dealers and clearing organizations	131,252	8,630
Deposits with clearing organizations	57,346	58,282
Accounts receivable	351,009	257,845
Other assets – Memberships in clearing organizations	3,268	3,127
Total assets measured at fair value	758,339	603,063
Liabilities
Payable to brokers and dealers and clearing organizations	130,651	3,363
Total	130,651	3,363
Quoted Prices in active Markets for Identical Assets (Level 1)
Assets
Total assets measured at fair value	1,966,335	2,053,289
Liabilities
Total		0
Quoted Prices in active Markets for Identical Assets (Level 1) \| Fair Value, Nonrecurring
Assets
Cash and restricted cash	215,464	275,179
Receivable from brokers and dealers and clearing organizations	0	0
Deposits with clearing organizations	57,346	58,282
Accounts receivable	0	0
Other assets – Memberships in clearing organizations	0	0
Total assets measured at fair value	272,810	333,461
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	29,566	24,411
Liabilities
Total		6,657
Significant Observable Inputs (Level 2) \| Fair Value, Nonrecurring
Assets
Cash and restricted cash	0	0
Receivable from brokers and dealers and clearing organizations	131,252	8,630
Deposits with clearing organizations	0	0
Accounts receivable	351,009	257,845
Other assets – Memberships in clearing organizations	0	0
Total assets measured at fair value	482,261	266,475
Liabilities
Payable to brokers and dealers and clearing organizations	130,651	3,363
Total	130,651	3,363
Significant Unobservable Inputs (Level 3)
Assets
Total assets measured at fair value	26,076	24,857
Liabilities
Total		0
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	3,268	3,127
Total assets measured at fair value	3,268	3,127
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
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-Publisher SEC

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

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-Topic 820
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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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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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