Condensed Consolidated Statements of Financial Condition - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets
Cash and cash equivalents	$ 331,668	$ 336,535
Cash segregated under regulatory requirements	196,448	80,243
Securities owned	60,146	58,408
Marketable securities	29,989	32,064
Receivables from broker-dealers, clearing organizations, customers and related broker-dealers	2,007,606	941,866
Accrued commissions and other receivables, net	596,126	516,091
Loans, forgivable loans and other receivables from employees and partners, net	240,283	216,868
Fixed assets, net	169,599	157,169
Investments	36,708	35,403
Goodwill	560,181	504,646
Other intangible assets, net	319,101	298,779
Receivables from related parties	11,229	7,748
Other assets	485,792	246,937
Total assets	5,044,876	3,432,757
Liabilities, Redeemable Partnership Interest, and Equity
Short-term borrowings	5,133	5,162
Repurchase agreements	4,327	986
Securities loaned	25,068	15,140
Accrued compensation	196,318	195,234
Payables to broker-dealers, clearing organizations, customers and related broker-dealers	1,805,004	769,833
Payables to related parties	38,132	40,155
Accounts payable, accrued and other liabilities	1,058,877	754,819
Notes payable and other borrowings	1,008,231	763,548
Total liabilities	4,141,090	2,544,877
Commitments, contingencies and guarantees (Note 19)
Redeemable partnership interest	25,140	24,706
Stockholders’ equity:
Additional paid-in capital	2,210,033	2,208,221
Treasury stock, at cost: 50,503 and 50,270 shares of Class A common stock at March 31, 2019 and December 31, 2018, respectively	(315,210)	(314,240)
Retained deficit	(1,090,585)	(1,105,019)
Accumulated other comprehensive income (loss)	(23,553)	(24,465)
Total stockholders’ equity	784,583	768,373
Noncontrolling interest in subsidiaries	94,063	94,801
Total equity	878,646	863,174
Total liabilities, redeemable partnership interest, and equity	5,044,876	3,432,757
Class A Common Stock [Member]
Stockholders’ equity:
Common stock value	3,439	3,417
Total equity	3,439	3,417
Class B Common Stock [Member]
Stockholders’ equity:
Common stock value	459	459
Total equity	$ 459	$ 459