Consolidated Statements of Financial Condition - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
ASSETS
Cash and cash equivalents	$ 413,612	$ 460,858
Cash segregated under federal regulations	50,108	50,059
Investments, at fair value	35,838	28,111
Accounts receivable, net of allowance of $57 and $163 as of June 30, 2021 and December 31, 2020, respectively	87,125	79,577
Receivables from broker-dealers, clearing organizations and customers	475,739	279,915
Goodwill	154,789	147,388
Intangible assets, net of accumulated amortization	119,989	95,354
Furniture, equipment, leasehold improvements and capitalized software, net of accumulated depreciation and amortization	93,108	85,204
Operating lease right-of-use assets	73,906	75,924
Prepaid expenses and other assets	33,709	29,039
Total assets	1,537,923	1,331,429
Liabilities
Accrued employee compensation	39,278	62,326
Payables to broker-dealers, clearing organizations and customers	278,303	133,326
Income and other tax liabilities	41,345	42,750
Accounts payable, accrued expenses and other liabilities	65,872	44,354
Operating lease liabilities	91,265	93,612
Total liabilities	516,063	376,368
Commitments and Contingencies (Note 13)
Stockholders' equity
Preferred stock
Common stock	123	123
Additional paid-in capital	313,683	329,742
Treasury stock - Common stock voting, at cost, 2,873,659 and 2,845,770 shares as of June 30, 2021 and December 31, 2020, respectively	(183,479)	(169,523)
Retained earnings	896,977	799,369
Accumulated other comprehensive loss	(5,444)	(4,650)
Total stockholders' equity	1,021,860	955,061
Total liabilities and stockholders' equity	1,537,923	1,331,429
Series A Preferred Stock [Member]
Stockholders' equity
Preferred stock