Condensed Consolidated Statements of Financial Condition - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Assets
Cash and cash equivalents	$ 398,469	$ 634,333
Restricted cash	258,677
Cash segregated under regulatory requirements	164,879	162,457
Securities owned	57,414	33,007
Marketable securities	78,109	208,176
Loans held for sale, at fair value	547,968	362,635
Receivables from broker-dealers, clearing organizations, customers and related broker-dealers	1,731,288	745,402
Mortgage servicing rights, net	392,040	392,626
Accrued commissions and other receivables, net	798,848	620,039
Loans, forgivable loans and other receivables from employees and partners, net	409,553	335,734
Fixed assets, net	210,462	189,347
Investments	167,759	141,788
Goodwill	946,855	945,582
Other intangible assets, net	298,109	311,021
Receivables from related parties	6,602	3,739
Other assets	381,641	343,826
Total assets	6,848,673	5,429,712
Liabilities, Redeemable Partnership Interest, and Equity
Short-term borrowings	5,187	6,046
Short-term borrowings from related parties	130,000
Repurchase agreements	3,108
Securities loaned	77,504	202,343
Warehouse notes payable	540,571	360,440
Accrued compensation	471,329	432,733
Payables to broker-dealers, clearing organizations, customers and related broker-dealers	1,516,934	607,580
Payables to related parties	77,620	40,988
Accounts payable, accrued and other liabilities	1,022,681	942,917
Notes payable and other borrowings	1,289,269	1,650,509
Total liabilities	5,134,203	4,243,556
Commitments, contingencies and guarantees (Note 23)
Redeemable partnership interest	47,116	46,415
Stockholders’ equity:
Additional paid-in capital	2,104,898	1,763,371
Treasury stock, at cost: 50,120 and 49,250 shares of Class A common stock at June 30, 2018 and December 31, 2017, respectively	(312,909)	(303,873)
Retained deficit	(860,107)	(859,009)
Accumulated other comprehensive income (loss)	(19,374)	(10,486)
Total stockholders’ equity	952,618	633,886
Noncontrolling interest in subsidiaries	714,736	505,855
Total equity	1,667,354	1,139,741
Total liabilities, redeemable partnership interest, and equity	6,848,673	5,429,712
Contingent Consideration Classified as Equity [Member]
Stockholders’ equity:
Contingent Class A common stock	36,352	40,472
Class A Common Stock [Member]
Stockholders’ equity:
Common stock value	3,410	3,063
Total equity	3,410	3,063
Class B Common Stock [Member]
Stockholders’ equity:
Common stock value	348	348
Total equity	$ 348	$ 348