Consolidated Statements of Financial Condition - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
ASSETS
Cash and cash equivalents	$ 390,915	$ 460,858
Cash segregated under federal regulations	50,083	50,059
Investments, at fair value	24,308	28,111
Accounts receivable, net of allowance of $107 and $163 as of March 31, 2021 and December 31, 2020, respectively	87,452	79,577
Receivables from broker-dealers, clearing organizations and customers	564,957	279,915
Goodwill	147,388	147,388
Intangible assets, net of accumulated amortization	90,945	95,354
Furniture, equipment, leasehold improvements and capitalized software, net of accumulated depreciation and amortization	88,655	85,204
Operating lease right-of-use assets	75,223	75,924
Prepaid expenses and other assets	25,943	29,039
Total assets	1,545,869	1,331,429
Liabilities
Accrued employee compensation	28,223	62,326
Payables to broker-dealers, clearing organizations and customers	308,268	133,326
Income and other tax liabilities	48,193	42,750
Accounts payable, accrued expenses and other liabilities	80,202	44,354
Operating lease liabilities	92,750	93,612
Total liabilities	557,636	376,368
Commitments and Contingencies (Note 13)
Stockholders' equity
Preferred stock
Common stock	123	123
Additional paid-in capital	309,988	329,742
Treasury stock - Common stock voting, at cost, 2,844,954 and 2,845,770 shares as of March 31, 2021 and December 31, 2020, respectively	(170,043)	(169,523)
Retained earnings	854,747	799,369
Accumulated other comprehensive loss	(6,582)	(4,650)
Total stockholders' equity	988,233	955,061
Total liabilities and stockholders' equity	1,545,869	1,331,429
Series A Preferred Stock [Member]
Stockholders' equity
Preferred stock