Consolidated Statements of Financial Condition - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
ASSETS
Cash and cash equivalents	$ 156,169	$ 167,014
Investments, at fair value	244,271	239,521
Accounts receivable, net of allowance of $96 and $178 as of March 31, 2018 and December 31, 2017, respectively	67,529	52,636
Goodwill and intangible assets, net of accumulated amortization	62,963	63,059
Furniture, equipment, leasehold improvements and capitalized software, net of accumulated depreciation and amortization	39,623	38,548
Prepaid expenses and other assets	17,888	18,717
Deferred tax assets, net	830	1,737
Total assets	589,273	581,232
Liabilities
Accrued employee compensation	15,611	36,502
Income and other tax liabilities	18,412	13,061
Deferred revenue	3,554	2,660
Accounts payable, accrued expenses and other liabilities	14,532	14,241
Total liabilities	52,109	66,464
Commitments and Contingencies (Note 10)
Stockholders' equity
Additional paid-in capital	327,669	331,081
Treasury stock - Common stock voting, at cost, 2,809,345 and 2,781,323 shares as of March 31, 2018 and December 31, 2017, respectively	(166,059)	(159,791)
Retained earnings	385,725	353,583
Accumulated other comprehensive loss	(10,292)	(10,226)
Total stockholders' equity	537,164	514,768
Total liabilities and stockholders' equity	589,273	581,232
Undefined Preferred Stock [Member]
Stockholders' equity
Preferred stock
Series A Preferred Stock [Member]
Stockholders' equity
Preferred stock
Voting Common Stock [Member]
Stockholders' equity
Common stock	$ 121	$ 121