The amount of expense recognized from issuing cash and stock awards to the employees and non-employees.

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Amount of judgment or settlement awarded to (against) the entity in respect of litigation, net of any reimbursement or proceeds from insurance carriers.

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Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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The amount of impairment loss recognized in the period resulting from the write-down of the carrying amount of a finite-lived intangible asset to fair value.

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Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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The amount of expense provided in the period for legal costs incurred on or before the balance sheet date pertaining to resolved, pending or threatened litigation, including arbitration and mediation proceedings.

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Amount of judgment or settlement awarded to (against) the entity in respect of litigation.

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Amount of receivable related to a loss contingency accrual. For example, an insurance recovery receivable.

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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The cash inflow from the amounts received by the insured under the terms of an insurance contract settlement. This element pertains only to insurance proceeds related to operating activities. It excludes insurance settlements classified as investing cash flows, for example, insurance settlements related to fixed assets.

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Amount after tax of reclassification adjustments of other comprehensive income (loss) attributable to parent.

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Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Segment Reporting - Financial Information (Details) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Sep. 30, 2017 USD ($) segment	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Segment reporting
Number of operating segments \| segment				4
Total Revenues	$ 114,531	$ 104,185		$ 356,947	$ 349,463
(Loss) income before income tax (benefit) expense	(1,955)	(27,798)		6,943	(41,094)
Identifiable assets	794,045	917,102		794,045	917,102	$ 775,285
Writen-off ITG Derivatives business				325
Restructuring charges					4,355
Cash and stock awards		500			3,800
Amounts reclassified from accumulated other comprehensive loss		1,066			1,066
Settlement agreement for termination of Former CEO
Segment reporting
Proceeds from insurer to settle claims		900
Legal Fees					2,700
Net litigation settlement amount					4,800
Insurance recovery		500			500
Settlement Agreement With SEC Involving Prereleased ADRs
Segment reporting
Litigation settlement amount		22,100
Legal Fees		1,600
Loss of Profits Due to Outage of Outsourced Primary Data Centre
Segment reporting
Proceeds from insurer to settle claims			$ 2,400
Reduction in trading and sales organizations and closing matched-book securities operations
Segment reporting
Restructuring charges			$ 4,400
U.S. Operations
Segment reporting
Total Revenues	47,403	48,774		153,559	173,677
(Loss) income before income tax (benefit) expense	(8,994)	(8,528)		(20,628)	(9,297)
Identifiable assets	338,000	418,357		338,000	418,357
Canadian Operations
Segment reporting
Total Revenues	15,055	13,719		47,521	45,605
(Loss) income before income tax (benefit) expense	1,405	1,496		8,034	7,616
Identifiable assets	75,332	108,647		75,332	108,647
European Operations
Segment reporting
Total Revenues	36,256	28,894		111,707	92,236
(Loss) income before income tax (benefit) expense	8,922	4,709		30,950	16,672
Identifiable assets	323,142	328,731		323,142	328,731
Asia Pacific Operations
Segment reporting
Total Revenues	15,327	12,502		42,990	34,539
(Loss) income before income tax (benefit) expense	2,938	901		6,318	208
Identifiable assets	57,571	61,367		57,571	61,367
Corporate Activity [Member]
Segment reporting
Total Revenues	490	296		1,170	3,406
(Loss) income before income tax (benefit) expense	(6,226)	(26,376)		(17,731)	(56,293)
Corporate
Segment reporting
Total Revenues	490	$ 296		1,170	$ 3,406
Matrix Holding Group
Segment reporting
Legal Fees	800
ITG Derivatives
Segment reporting
Total Revenues				3,800
Writen-off ITG Derivatives business	$ 300			300
Currency translation adjustment
Segment reporting
Amounts reclassified from accumulated other comprehensive loss				$ (1,100)