Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Consolidated net income (loss)	$ 87,174	$ 97,431
Less: Consolidated net income from discontinued operations, net of tax		(24,759)
Adjustments to reconcile consolidated net income (loss) to net cash provided by (used in) operating activities:
Fixed asset depreciation and intangible asset amortization	18,464	17,681
Employee loan amortization and reserves on employee loans	6,574	1,569
Equity-based compensation and allocations of net income to limited partnership units and FPUs	12,141	39,408
Deferred compensation expense	(7)	1,311
Losses (gains) on equity method investments	(783)	(2,624)
Amortization of discount (premium) on notes payable	519	(931)
Unrealized (gain) loss on marketable securities	21	(7,150)
Impairment of fixed assets, intangible assets and investments	357
Deferred tax provision (benefit)	(1,896)	2,662
Realized losses (gains) on marketable securities	(2,487)	(2,101)
Change in estimated acquisition earn-out payables	(1,482)	(841)
Loss (gains) on other investments	(20,395)	(20,579)
Consolidated net income (loss), adjusted for non-cash and non-operating items	98,200	101,077
Decrease (increase) in operating assets:
Securities owned	(1,738)	(56,350)
Securities borrowed		(309)
Receivables from broker-dealers, clearing organizations, customers and related broker-dealers	(1,065,889)	(650,170)
Accrued commissions receivable, net	(46,275)	(85,658)
Loans, forgivable loans and other receivables from employees and partners, net	(28,420)	(18,450)
Receivables from related parties	(882)	(148,796)
Other assets	(12,431)	(18,115)
Increase (decrease) in operating liabilities:
Repurchase Agreements	3,341	985
Securities loaned	9,928	(60,777)
Accrued compensation	(21,688)	(3,939)
Payables to broker-dealers, clearing organizations, customers and related broker-dealers	1,035,134	603,929
Payables to related parties	(2,023)	(15,930)
Accounts payable, accrued and other liabilities	(28,035)	5,245
Net cash provided by (used in) operating activities	(60,778)	(347,258)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of fixed assets	(12,123)	(8,065)
Capitalization of software development costs	(6,259)	(10,837)
Purchase of equity method investments	(368)	(123)
Proceeds from equity method investments		1,814
Payments for acquisitions, net of cash and restricted cash acquired	26,265
Proceeds from sale of marketable securities	4,553	72,366
Net cash (used in) provided by investing activities	12,068	55,155
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayments of long-term debt and collateralized borrowings	(3,731)	(3,601)
Issuance of long-term debt and collateralized borrowings, net of deferred issuance costs	249,450
Earnings distributions	(27,188)	(51,225)
Redemption and repurchase of limited partnership interests	(5,201)	(4,496)
Dividends to stockholders	(47,434)	(55,576)
Repurchase of Class A common stock	(1,236)
Proceeds from issuance of Class A common stock, net of costs		246,704
Loan to related parties		180,000
Payments on acquisition earn-outs	(5,903)	(4,303)
Net cash (used in) provided by financing activities	158,757	307,503
Net cash provided by (used in) operating activities from discontinued operations		(485,477)
Net cash provided by (used in) investing activities from discontinued operations		40,822
Net cash provided by (used in) financing activities from discontinued operations		29,321
Effect of exchange rate changes on Cash and cash equivalents, Restricted cash and Cash segregated under regulatory requirements	1,291	3,870
Net (decrease) increase in Cash and cash equivalents, Restricted cash and Cash segregated under regulatory requirements	111,338	(396,064)
Cash and cash equivalents, Restricted cash and Cash segregated under regulatory requirements at beginning of period	416,778	796,790
Cash and cash equivalents, Restricted cash and Cash segregated under regulatory requirements at end of period	528,116	400,726
Supplemental cash information:
Cash paid during the period for taxes	5,722	12,448
Cash paid during the period for interest	13,835	11,412
Supplemental non-cash information:
Issuance of Class A common stock upon exchange of limited partnership interests	9,736	40,754
Issuance of Class A and contingent Class A common stock and limited partnership interests for acquisitions	$ 1,874	$ 4,027