Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash Flows from Operating Activities:
Net income	$ 1,342	$ 9,945
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	22,220	22,437
Deferred income tax expense (benefit)	729	(7,407)
Provision for doubtful accounts	192	155
Non-cash share-based compensation	14,154	10,818
Changes in operating assets and liabilities:
Deposits with clearing organizations	(24,118)	(9,673)
Securities owned, at fair value	620	634
Receivables from brokers, dealers and clearing organizations	(74,048)	(83,582)
Receivables from customers	(93,681)	(117,877)
Accounts payable and accrued expenses	33,964	(29,254)
Payables to brokers, dealers and clearing organizations	63,422	90,673
Payables to customers	92,600	91,320
Securities sold, not yet purchased, at fair value	(1)	(249)
Income taxes receivable/payable	2,074	1,314
Other, net	(20,011)	290
Net cash provided by (used in) operating activities	19,458	(20,456)
Cash Flows from Investing Activities:
Investment in venture	(612)
Capital purchases	(7,534)	(5,657)
Capitalization of software development costs	(13,380)	(14,357)
Net cash used in investing activities	(21,526)	(20,014)
Cash Flows from Financing Activities:
Repayments of long term debt	(775)	(3,317)
Proceeds from (repayments of) borrowing under short-term bank loans	(26,623)	13,359
Debt issuance costs	(751)	(762)
Common stock issued	733	745
Common stock repurchased	(5,736)	(4,983)
Dividends paid	(4,581)	(4,595)
Shares withheld for net settlements of share-based awards	(8,366)	(9,882)
Net cash used in financing activities	(46,099)	(9,435)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(3,175)	520
Net decrease in cash, cash equivalents and restricted cash	(51,342)	(49,385)
Cash, cash equivalents and restricted cash—beginning of period	306,051	318,330
Cash, cash equivalents and restricted cash—end of period	254,709	268,945
Supplemental cash flow information:
Interest paid	2,775	2,326
Income taxes paid, net	1,496	$ 4,859
Supplemental disclosure of non-cash investing and financing activities:
Investment in venture	$ 1,393