Condensed Consolidated Statements of Financial Condition - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets
Cash and cash equivalents	$ 413,951	$ 336,535
Cash segregated under regulatory requirements	223,529	80,243
Securities owned	60,398	58,408
Marketable securities	13,220	32,064
Receivables from broker-dealers, clearing organizations, customers and related broker-dealers	3,469,098	941,866
Accrued commissions and other receivables, net	535,553	516,091
Loans, forgivable loans and other receivables from employees and partners, net	266,920	216,868
Fixed assets, net	195,380	157,169
Investments	35,969	35,403
Goodwill	552,427	504,646
Other intangible assets, net	308,500	298,779
Receivables from related parties	9,094	7,748
Other assets	464,018	246,937
Total assets	6,548,057	3,432,757
Liabilities, Redeemable Partnership Interest, and Equity
Short-term borrowings	4,803	5,162
Repurchase agreements	1,895	986
Securities loaned	13,000	15,140
Accrued compensation	216,062	195,234
Payables to broker-dealers, clearing organizations, customers and related broker-dealers	3,299,451	769,833
Payables to related parties	97,836	40,155
Accounts payable, accrued and other liabilities	985,413	754,819
Notes payable and other borrowings	1,105,498	763,548
Total liabilities	5,723,958	2,544,877
Commitments, contingencies and guarantees (Note 19)
Redeemable partnership interest	24,560	24,706
Stockholders’ equity:
Additional paid-in capital	2,243,889	2,208,221
Treasury stock, at cost: 50,525 and 50,270 shares of Class A common stock at September 30, 2019 and December 31, 2018, respectively	(315,308)	(314,240)
Retained deficit	(1,176,741)	(1,105,019)
Accumulated other comprehensive income (loss)	(33,652)	(24,465)
Total stockholders’ equity	722,175	768,373
Noncontrolling interest in subsidiaries	77,364	94,801
Total equity	799,539	863,174
Total liabilities, redeemable partnership interest, and equity	6,548,057	3,432,757
Class A Common Stock [Member]
Stockholders’ equity:
Common stock value	3,528	3,417
Class B Common Stock [Member]
Stockholders’ equity:
Common stock value	$ 459	$ 459