Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash Flows from Operating Activities:
Net income	$ 4,377	$ 5,302
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	11,230	11,227
Deferred income tax expense (benefit)	841	(4,208)
Provision for doubtful accounts	133	(12)
Non-cash share-based compensation	8,295	5,687
Changes in operating assets and liabilities:
Deposits with clearing organizations	(12,757)	5,664
Securities owned, at fair value	303	408
Receivables from brokers, dealers and clearing organizations	5,467	(124,963)
Receivables from customers	(40,873)	(39,774)
Accounts payable and accrued expenses	4,878	(39,510)
Payables to brokers, dealers and clearing organizations	10,192	83,338
Payables to customers	16,871	10,314
Securities sold, not yet purchased, at fair value	(1)	(248)
Income taxes receivable/payable	2,412	(94)
Other, net	(20,873)	(2,169)
Net cash used in operating activities	(9,505)	(89,038)
Cash Flows from Investing Activities:
Investment in venture	(612)
Capital purchases	(3,517)	(3,129)
Capitalization of software development costs	(6,070)	(7,100)
Net cash used in investing activities	(10,199)	(10,229)
Cash Flows from Financing Activities:
Repayments of long term debt	(595)	(1,565)
Proceeds from (repayments of) borrowing under short-term bank loans	(20,997)	57,587
Debt issuance costs	(751)	(756)
Common stock issued	166	185
Common stock repurchased	(3,571)	(3,210)
Dividends paid	(2,293)	(2,300)
Shares withheld for net settlements of share-based awards	(8,321)	(9,851)
Net cash (used in) provided by financing activities	(36,362)	40,090
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(429)	(217)
Net decrease in cash, cash equivalents and restricted cash	(56,495)	(59,394)
Cash, cash equivalents and restricted cash—beginning of period	306,051	318,330
Cash, cash equivalents and restricted cash—end of period	249,556	258,936
Supplemental cash flow information:
Interest paid	1,582	1,133
Income taxes paid		$ 2,829
Proceeds from income tax refunds	1,587
Supplemental disclosure of non-cash investing and financing activities:
Investment in venture	$ 1,393