Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from Operating Activities:
Net income (loss)	$ 9,945	$ (7,723)
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Depreciation and amortization	22,437	21,684
Deferred income tax benefit	(7,407)	(4,415)
Provision for doubtful accounts	155	18
Non-cash share based compensation	10,818	14,488
Gain on sale of investment research operations		(21)
Changes in operating assets and liabilities:
Cash restricted or segregated under regulations and other	23,631	(428)
Deposits with clearing organizations	(9,673)	(27,250)
Securities owned, at fair value	634	1,275
Receivables from brokers, dealers and clearing organizations	(83,582)	634,175
Receivables from customers	(117,877)	(136,599)
Accounts payable and accrued expenses	(29,254)	(5,898)
Payables to brokers, dealers and clearing organizations	90,673	(690,584)
Payables to customers	91,320	64,422
Securities sold, not yet purchased, at fair value	(249)	(1,016)
Income taxes receivable/payable	1,314	(11,585)
Excess tax benefit from share-based payment arrangements		(989)
Other, net	290	(4,320)
Net cash provided by (used in) operating activities	3,175	(154,766)
Cash flows from Investing Activities:
Capital purchases	(5,657)	(5,493)
Capitalization of software development costs	(14,357)	(12,670)
Proceeds from sale of investment research operations, net of deal costs		6,125
Net cash used in investing activities	(20,014)	(12,038)
Cash flows from Financing Activities:
Repayments of long term debt	(3,317)	(3,109)
Proceeds from borrowing under short-term bank loans	13,359	84,071
Debt issuance costs	(762)	(810)
Excess tax benefit from share-based payment arrangements		989
Common stock issued	745	3,075
Common stock repurchased	(4,983)	(14,946)
Dividends paid	(4,595)	(4,601)
Shares withheld for net settlements of share-based awards	(9,882)	(6,529)
Net cash (used in) provided by financing activities	(9,435)	58,140
Effect of exchange rate changes on cash and cash equivalents	260	15,523
Net increase (decrease) in cash and cash equivalents	(26,014)	(93,141)
Cash and cash equivalents - beginning of year	277,977	330,653
Cash and cash equivalents - end of period	251,963	237,512
Supplemental cash flow information:
Interest paid	2,326	2,156
Income taxes paid	$ 4,859	$ 10,336