Gfi (GFIG) 10-Q 8 Nov 13 2013 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2013	Oct. 31, 2013
Document and Entity Information	'	'
Entity Registrant Name	'GFI Group Inc.	'
Entity Central Index Key	'0001292426	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-13	'
Amendment Flag	'false	'
Current Fiscal Year End Date	'--12-31	'
Entity Current Reporting Status	'Yes	'
Entity Filer Category	'Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	123,028,840
Document Fiscal Year Focus	'2013	'
Document Fiscal Period Focus	'Q3	'

CONDENSED_CONSOLIDATED_STATEME

CONDENSED CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (UNAUDITED) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Assets	'	'
Cash and cash equivalents	$168,878	$227,441
Cash and securities segregated under federal and other regulations	60,783	47,494
Commissions receivable, net of allowance for doubtful accounts of $1,803 and $1,710 at September 30, 2013 and December 31, 2012, respectively	94,905	73,930
Receivables from brokers, dealers and clearing organizations	647,029	252,696
Property, equipment and leasehold improvements, net of depreciation and amortization of $184,018 and $169,663 at September 30, 2013 and December 31, 2012, respectively	63,149	58,835
Goodwill	267,771	267,977
Intangible assets, net	42,672	48,492
Other assets	186,563	203,196
TOTAL ASSETS	1,531,750	1,180,061
LIABILITIES	'	'
Accrued compensation	63,045	79,195
Accounts payable and accrued expenses	48,830	36,674
Payables to brokers, dealers and clearing organizations	513,060	164,935
Payables to clearing services customers	136,215	139,627
Short-term borrowings	10,000	'
Long-term obligations	240,000	250,000
Other liabilities	85,511	83,574
Total Liabilities	1,096,661	754,005
Commitments and contingencies (Note 11)	'	'
STOCKHOLDERS' EQUITY	'	'
Preferred stock, $0.01 par value; 5,000,000 shares authorized, none outstanding at September 30, 2013 and December 31, 2012	'	'
Common stock, $0.01 par value; 400,000,000 shares authorized; 140,310,036 and 134,689,148 shares issued at September 30, 2013 and December 31, 2012, respectively	1,403	1,347
Additional paid in capital	387,327	374,798
Retained earnings	120,224	121,415
Treasury stock, 17,491,081 and 17,313,686 shares of common stock at cost, at September 30, 2013 and December 31, 2012, respectively	-75,439	-75,020
Accumulated other comprehensive income	137	2,542
Total Stockholders' Equity	433,652	425,082
Non-controlling interests	1,437	974
Total Equity	435,089	426,056
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$1,531,750	$1,180,061

CONDENSED_CONSOLIDATED_STATEME1

CONDENSED CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (UNAUDITED) (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, except Share data, unless otherwise specified
CONDENSED CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION	'	'
Commissions receivable, allowance for doubtful accounts	$1,803	$1,710
Property, equipment and leasehold improvements, depreciation and amortization	$184,018	$169,663
Preferred stock, par value (in dollars per share)	$0.01	$0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$0.01	$0.01
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	140,310,036	134,689,148
Treasury stock, common shares at cost	17,491,081	17,313,686

CONDENSED_CONSOLIDATED_STATEME2

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues	'	'	'	'
Agency commissions	$109,365	$112,239	$358,413	$380,276
Principal transactions	41,841	50,278	143,468	164,830
Total brokerage revenues	151,206	162,517	501,881	545,106
Clearing services revenues	32,722	30,545	110,225	88,307
Interest income from clearing services	455	422	1,623	1,325
Equity in net earnings of unconsolidated businesses	1,566	2,344	6,925	6,242
Software, analytics and market data	22,472	21,204	66,438	61,671
Other income	4,012	2,356	12,011	14,642
Total revenues	212,433	219,388	699,103	717,293
Interest and transaction-based expenses	'	'	'	'
Transaction fees on clearing services	31,620	29,420	106,952	84,988
Transaction fees on brokerage services	4,430	5,734	15,572	18,012
Interest expense from clearing services	143	82	390	680
Total interest and transaction-based expenses	36,193	35,236	122,914	103,680
Revenues, net of interest and transaction-based expenses	176,240	184,152	576,189	613,613
Expenses	'	'	'	'
Compensation and employee benefits	121,109	130,499	392,737	421,927
Communications and market data	13,747	15,269	41,077	46,629
Travel and promotion	7,380	7,973	23,298	27,347
Rent and occupancy	7,901	7,083	22,152	20,759
Depreciation and amortization	8,320	9,246	24,962	27,502
Professional fees	5,712	5,925	18,824	17,470
Interest on borrowings	7,612	6,738	22,475	20,080
Other expenses	5,615	8,586	24,138	23,730
Total other expenses	177,396	191,319	569,663	605,444
(Loss) income before (benefit from) provision for income taxes	-1,156	-7,167	6,526	8,169
(Benefit from) provision for income taxes	-1,127	1,638	-5,267	6,699
Net (loss) income before attribution to non-controlling stockholders	-29	-8,805	11,793	1,470
Less: Net income (loss) attributable to non-controlling interests	432	-112	889	51
GFI's net (loss) income	($461)	($8,693)	$10,904	$1,419
(Loss) earnings per share available to common stockholders	'	'	'	'
Basic (in dollars per share)	$0	($0.08)	$0.09	$0.01
Diluted (in dollars per share)	$0	($0.08)	$0.09	$0.01
Weighted average shares outstanding	'	'	'	'
Basic (in shares)	120,331,179	115,541,373	118,138,756	116,073,488
Diluted (in shares)	120,331,179	115,541,373	126,858,459	123,570,110
Dividends declared per share of common stock (in dollars per share)	$0.05	$0.05	$0.10	$0.15

CONDENSED_CONSOLIDATED_STATEME3

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (UNAUDITED) (USD $)	3 Months Ended				9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)	'		'		'		'
Net (loss) income before attribution to non-controlling stockholders	($29)		($8,805)		$11,793		$1,470
Other comprehensive income (loss):	'		'		'		'
Foreign currency translation adjustment	7,722		6,041		-3,074		7,721
Unrealized gain on available-for-sale securities, net of tax	316	[1]	343	[1]	748	[1]	266	[1]
Total other comprehensive income (loss)	8,038		6,384		-2,326		7,987
Comprehensive income (loss) including non-controlling stockholders	8,009		-2,421		9,467		9,457
Comprehensive (loss) income attributable to non-controlling stockholders	595		-111		968		62
GFI's comprehensive income (loss)	$7,414		($2,310)		$8,499		$9,395
[1]	(1) Amounts are net of provision for income taxes of $97 and $116 for the three months ended September 30, 2013 and 2012, respectively. Amounts are net of provision for income taxes of $227 and $79 for the nine months ended September 30, 2013 and 2012, respectively.

CONDENSED_CONSOLIDATED_STATEME4

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (UNAUDITED) (Parenthetical) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)	'	'	'	'
Unrealized gain on available-for-sale securities, provision for income taxes	$97	$116	$227	$79

CONDENSED_CONSOLIDATED_STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
CASH FLOWS FROM OPERATING ACTIVITIES:	'	'
Net (loss) income before attribution to non-controlling stockholders	$11,793	$1,470
Adjustments to reconcile net income to net cash (used in) provided by operating activities:	'	'
Depreciation and amortization	24,962	27,502
Share-based compensation expense	22,414	24,666
Tax expense related to share-based compensation	1,877	2,141
Amortization of prepaid bonuses and forgivable loans	19,904	19,727
Benefit from deferred taxes	-12,155	-5,536
Losses (gains) on foreign exchange derivative contracts, net	1,516	-3,327
Earnings from equity method investments, net	-1,931	-319
Amortization of deferred financing fees	1,649	1,633
Impairment of investments	'	5,362
Mark-to-market of future purchase commitment	-2,203	-9,098
Translation gain on liquidation of foreign subsidiary	-1,645	'
Other non-cash charges, net	257	2,472
(Increase) decrease in operating assets:	'	'
Cash and securities segregated under federal and other regulations	-13,289	-25,223
Commissions receivable	-21,460	1,651
Receivables from brokers, dealers and clearing organizations	-394,333	-361,284
Other assets	15,098	-21,377
Increase (decrease) in operating liabilities:	'	'
Accrued compensation	-16,150	-57,989
Accounts payable and accrued expenses	12,006	-15,093
Payables to brokers, dealers and clearing organizations	348,125	273,254
Payables to clearing services customers	-3,412	142,776
Other liabilities	4,235	7,710
Cash (used in) provided by operating activities	-2,742	11,118
CASH FLOWS FROM INVESTING ACTIVITIES:	'	'
Proceeds from other investments	3,030	1,106
Purchases of other investments	-14,779	-3,121
Purchase of property, equipment and leasehold improvements	-10,213	-3,964
Payments for internally developed software	-7,525	-8,679
Proceeds on foreign exchange derivative contracts	1,377	5,774
Payments on foreign exchange derivative contracts	-2,445	-2,201
Other investing activities, net	-624	'
Cash used in investing activities	-31,179	-11,085
CASH FLOWS FROM FINANCING ACTIVITIES:	'	'
Proceeds from short-term borrowings	125,000	185,000
Repayment of short-term borrowings	-115,000	-185,000
Repurchase and retirement of a portion of long-term borrowings	-9,385	'
Purchases of treasury stock	'	-9,939
Cash dividends paid to common stockholders	-12,095	-17,761
Cash dividends paid to non-controlling interests	-231	-256
Payment of debt issuance costs	-870	-134
Proceeds from exercise of stock options	662	'
Shares withheld for taxes on vested restricted stock units	-8,679	-9,182
Payment of contingent consideration liabilities	-350	-478
Payment of future purchase commitment	-798	'
Tax expense related to share-based compensation	-1,877	-2,141
Cash used in financing activities	-23,623	-39,891
Effects of exchange rate changes on cash and cash equivalents	-1,019	3,738
DECREASE IN CASH AND CASH EQUIVALENTS	-58,563	-36,120
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	227,441	245,879
CASH AND CASH EQUIVALENTS, END OF PERIOD	168,878	209,759
SUPPLEMENTAL DISCLOSURE:	'	'
Cash paid for interest	25,687	24,094
Cash paid for income taxes	10,189	9,649
Cash received from income tax refunds	$2,382	$1,512

CONDENSED_CONSOLIDATED_STATEME6

CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY (UNAUDITED) (USD $)	Total		Total Stockholders' Equity	Common Stock	Additional Paid In Capital	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive (Income) Loss	Non-Controlling Interests
In Thousands, unless otherwise specified
Balance at Dec. 31, 2012	$426,056		$425,082	$1,347	$374,798	($75,020)	$121,415	$2,542	$974
Increase (Decrease) in Stockholders' Equity	'		'	'	'	'	'	'	'
Issuance of treasury stock	-1		-1	'	418	-419	'	'	'
Issuance of common stock for exercise of stock options and vesting of restricted stock units	662		662	43	619	'	'	'	'
Withholding of restricted stock units in satisfaction of tax requirements	-8,679		-8,679	'	-8,679	'	'	'	'
Tax expense associated with share-based awards	-1,877		-1,877	'	-1,877	'	'	'	'
Foreign currency translation adjustment	-3,074		-3,153	'	'	'	'	-3,153	79
Unrealized gain on available-for-sale securities, net of tax	748	[1]	748	'	'	'	'	748	'
Dividends to stockholders	-12,326		-12,095	'	'	'	-12,095	'	-231
Share-based compensation	22,061		22,061	'	22,061	'	'	'	'
Issuance of contingently issuable shares	'		'	13	-13	'	'	'	'
Other, net	-274		'	'	'	'	'	'	-274
Net income	11,793		10,904	'	'	'	10,904	'	889
Balance at Sep. 30, 2013	$435,089		$433,652	$1,403	$387,327	($75,439)	$120,224	$137	$1,437
[1]	(1) Amounts are net of provision for income taxes of $97 and $116 for the three months ended September 30, 2013 and 2012, respectively. Amounts are net of provision for income taxes of $227 and $79 for the nine months ended September 30, 2013 and 2012, respectively.

ORGANIZATION_AND_BUSINESS

ORGANIZATION AND BUSINESS	9 Months Ended
	Sep. 30, 2013
ORGANIZATION AND BUSINESS	'
ORGANIZATION AND BUSINESS	'
	1.              ORGANIZATION AND BUSINESS
	The Condensed Consolidated Financial Statements include the accounts of GFI Group Inc. and its subsidiaries (collectively, “GFI” or the “Company”). The Company, through its subsidiaries, provides wholesale brokerage and trade execution services, clearing services and trading system software products to institutional clients in markets for a range of fixed income, financial, equity and commodity products. The Company complements its brokerage and trade execution capabilities with value-added services, such as market data and analytical software products for trader and back-office support, which it licenses primarily to companies in the financial services industry. As of September 30, 2013, Jersey Partners, Inc. (“JPI”) owned approximately 38% of the Company’s outstanding shares of common stock. The Company’s executive chairman, Michael Gooch, is the controlling shareholder of JPI.

SUMMARY_OF_SIGNIFICANT_ACCOUNT

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	9 Months Ended
	Sep. 30, 2013
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	'
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	'
	2.              SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	Basis of Presentation—The Company’s Condensed Consolidated Financial Statements (Unaudited) are prepared in accordance with accounting principles generally accepted in the United States of America, which require management to make estimates and assumptions that affect the reported amounts of assets and liabilities, revenues and expenses, and the disclosure of contingencies in the Condensed Consolidated Financial Statements. Certain estimates and assumptions relate to the accounting for acquired goodwill and intangible assets, fair value measurements, compensation accruals, tax assets and liabilities, and the potential outcome of litigation matters. Management believes that the estimates utilized in the preparation of the Condensed Consolidated Financial Statements are reasonable and prudent. Actual results could differ materially from these estimates.
	Certain amounts in the Condensed Consolidated Statements of Cash Flows have been reclassified to conform to the current year presentation.
	These Condensed Consolidated Financial Statements are unaudited and should be read in conjunction with the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2012. References to the Company’s “2012 Form 10-K” are to the Company’s Annual Report on Form 10-K for the year ended December 31, 2012. The condensed consolidated financial information as of December 31, 2012 presented in this Form 10-Q has been derived from audited Consolidated Financial Statements not included herein.
	These unaudited Condensed Consolidated Financial Statements reflect all adjustments that are, in the opinion of management, necessary for a fair statement of the results for the interim periods presented. These adjustments are of a normal, recurring nature. Interim period operating results may not be indicative of the operating results for a full year.
	Consolidation Policies
	General—The Condensed Consolidated Financial Statements include the accounts of the Company, its wholly-owned subsidiaries and subsidiaries that are treated as such and other entities in which the Company has a controlling financial interest. For consolidated subsidiaries that are less than wholly-owned, equity interests that are not owned by the Company are referred to as non-controlling interests. The portion of net income attributable to non-controlling interests for such subsidiaries is presented as Net income attributable to non-controlling interests on the Condensed Consolidated Statements of Operations, and the portion of the stockholders’ equity of such subsidiaries is presented as Non-controlling interests in the Condensed Consolidated Statements of Financial Condition and Condensed Consolidated Statement of Changes in Stockholders’ Equity. All intercompany transactions and balances have been eliminated.
	Variable Interest Entities—The Company determines whether it holds any interests in entities deemed to be a variable interest entity (“VIE”). A VIE is an entity that lacks one or more of the following characteristics (i) the total equity investment at risk is sufficient to enable the entity to finance its activities independently and (ii) the equity holders have the power to direct the activities of the entity that most significantly impact its economic performance, the obligation to absorb the losses of the entity and the right to receive the residual returns of the entity. The Company has a controlling financial interest and will consolidate a VIE if it is the primary beneficiary.
	The primary beneficiary is the party that has both (i) the power to direct the activities of the VIE that most significantly impact the economic performance of the entity and (ii) the obligation to absorb losses of the entity that could be potentially significant to the VIE or the right to receive benefits from the entity that could be potentially significant.
	As of September 30, 2013, the company holds interests in certain VIEs. One of these VIEs is consolidated because it was determined that the Company is the primary beneficiary of this VIE because (1) the Company provided the majority of the VIE’s start-up capital and (2) the Company has consent rights regarding those activities that the Company believes would most significantly impact the economic performance of the entity. The remaining VIEs are not consolidated as it was determined that the Company is not the primary beneficiary based on the level of equity ownership and voting power. The Company reassesses its evaluation of whether an entity is a VIE when certain events occur, such as changes in economic ownership and voting power. The Company reassesses its determination of whether it is the primary beneficiary of a VIE on an ongoing basis based on current facts and circumstances.  See Note 15 for disclosures on Variable Interest Entities.
	Cash and Cash Equivalents—Cash and cash equivalents consist of cash and highly liquid investments with maturities, when purchased, of three months or less.
	Cash and Securities Segregated Under Federal and Other Regulations—The Company holds cash and securities representing funds received in connection with customer trading activities. The Company’s subsidiaries are required to satisfy regulations mandated by their primary regulators to segregate or set aside cash or equivalent securities to satisfy regulations, promulgated to protect customer assets.
	Commissions Receivable—Commissions receivable represents amounts due from brokers, dealers, banks and other financial and nonfinancial institutions for the execution of securities, commodities, foreign exchange and other derivative brokerage transactions. In estimating the allowance for doubtful accounts, management considers the length of time receivables are past due and historical experience. In addition, if the Company is aware of a client’s inability to meet its financial obligations, a specific provision for doubtful accounts is recorded in the amount of the estimated losses that will result from the inability of that client to meet its financial obligation.
	Receivables from and Payables to Brokers, Dealers and Clearing Organizations—Receivables from and payables to brokers, dealers and clearing organizations primarily represent: (i) principal transactions for which the stated settlement dates have not yet been reached, (ii) principal transactions which have not settled as of their stated settlement dates, (iii) cash, including deposits, held at clearing organizations and exchanges in support of the Company’s clearing business and to facilitate settlement and clearance of matched principal transactions and (iv) the spread on matched principal transactions that have not yet been remitted from/to clearing organizations and exchanges.
	Property, Equipment and Leasehold Improvements—Property, equipment and leasehold improvements are stated at cost, less accumulated depreciation and amortization. Depreciation and amortization are calculated using the straight-line method, generally over three to seven years. Property and equipment are depreciated over their estimated useful lives. Leasehold improvements are amortized over the shorter of the remaining term of the respective lease to which they relate or the remaining useful life of the leasehold improvement. Internal and external costs incurred in developing or obtaining computer software for internal use are capitalized in accordance with Accounting Standards Codification (“ASC”) 350 Intangibles—Goodwill and Other (“ASC 350”), and are amortized on a straight-line basis over the estimated useful life of the software, generally three years. General and administrative costs related to developing or obtaining such software are expensed as incurred.
	Goodwill and Intangible Assets—Goodwill represents the excess of the purchase price allocation over the fair value of tangible and identifiable intangible net assets acquired. The goodwill associated with each business combination is allocated to the related reporting units, which are determined based on how the Company’s businesses are managed and how they are reviewed by the Company’s chief operating decision maker. Other intangible assets are recorded at their fair value upon completion of a business combination or certain other transactions.
	In accordance with ASC 350, goodwill and other intangible assets with indefinite lives are not amortized, but instead are periodically tested for impairment. The Company reviews goodwill and other intangible assets with indefinite lives for impairment on an annual basis as of November 1 of each fiscal year or whenever an event occurs or circumstances change that could reduce the fair value of a reporting unit below its carrying amount.
	Intangible assets with definite lives are amortized on a straight-line basis over their estimated useful lives. See Note 5 for further information.
	Prepaid Bonuses and Forgivable Employee Loans—Prepaid bonuses and forgivable loans to employees are stated at historical value net of amortization when the agreement between the Company and the employee provides for the return of proportionate amounts of the bonus or loan outstanding if employment is terminated in certain circumstances prior to the end of the term of the agreement. Amortization is calculated using the straight-line method over the term of the contract, which is generally two to four years, and is recorded in Compensation and employee benefits. The Company generally expects to recover the unamortized portion of prepaid bonuses and forgivable loans when employees voluntarily terminate their employment or if their employment is terminated for cause prior to the end of the term of the agreement. The prepaid bonuses and forgivable loans are included in Other assets in the Condensed Consolidated Statements of Financial Condition. At September 30, 2013 and December 31, 2012, the Company had prepaid bonuses of $25,833 and $31,847, respectively. At September 30, 2013 and December 31, 2012, the Company had forgivable employee loans and advances to employees of $26,009 and $31,655, respectively. Amortization of prepaid bonuses and forgivable employee loans for the nine months ended September 30, 2013 and 2012 was $19,904 and $19,727, respectively and is included within Compensation and employee benefits.
	Investments— When the Company does not have a controlling financial interest in an entity but can exert significant influence over the entity’s operating and financial policies, the investment is accounted for under the equity method of accounting in accordance with ASC 323-10, Investments—Equity Method and Joint Ventures (“ASC 323-10”). Significant influence generally exists when the Company owns 20% to 50% of the entity’s common stock or in-substance common stock. The Company initially records the investment at cost and adjusts the carrying amount each period to recognize its share of the earnings or losses of the investee based on the percentage of ownership. At September 30, 2013 and December 31, 2012, the Company had equity method investments with a carrying value of $37,057 and $26,743, respectively, included within Other assets. The Company also provides clearing and other administrative services to certain of these equity method investees.
	Investments for which the Company does not have the ability to exert significant influence over operating and financial policies are generally accounted for using the cost method of accounting in accordance with ASC 325-10, Investments—Other (“ASC 325-10”). At September 30, 2013 and December 31, 2012, the Company had cost method investments of $5,064 and $4,671, respectively, included within Other assets. The fair value of the Company’s cost method investments are not estimated if there are no identified events or changes in circumstances that may have a significant adverse effect on the fair value. The Company monitors its equity and cost method investments for indicators of impairment each reporting period.
	The Company accounts for its marketable equity securities and its debt securities in accordance with ASC 320-10, Investments—Debt and Equity Securities. Investments that are owned by the Company’s broker-dealer subsidiaries are recorded at fair value with realized and unrealized gains and losses reported in net income. Investments designated as available-for-sale that are owned by the Company’s non broker-dealer subsidiaries are recorded at fair value with unrealized gains or losses reported as a separate component of other comprehensive income, net of tax. The fair value of the Company’s available-for-sale securities was $4,354 and $3,355 as of September 30, 2013 and December 31, 2012, respectively, and is included within Other assets.
	Fair Value of Financial Instruments—In accordance with ASC 820-10, Fair Value Measurements and Disclosures (“ASC 820-10”), the Company estimates fair values of financial instruments using relevant market information and other assumptions. Fair value estimates involve uncertainties and matters of significant judgment in interpreting market data and, accordingly, changes in assumptions or in market conditions could adversely affect the estimates. The Company also discloses the fair value of its financial instruments in accordance with the fair value hierarchy as set forth by ASC 820-10. See Note 13 for further information.
	Fair Value Option—In accordance with ASC 825-10-25, Financial Instruments - Recognition, upon the acquisition of The Kyte Group Limited and Kyte Capital Management Limited (collectively “Kyte”), the Company elected the fair value option to account for its then future commitment to purchase the remaining 30% equity interest in Kyte.  See Note 4 for further discussion regarding this future purchase commitment.
	The fair value option election allows companies to irrevocably elect fair value as the initial and subsequent measurement attribute for certain financial assets and liabilities. Any change in fair value for assets and liabilities for which the election is made is to be recognized in earnings as they occur. The fair value option election is permitted on an instrument by instrument basis at initial recognition of an asset or liability or upon an event that gives rise to a new basis of accounting for that instrument.
	The primary reason for electing the fair value option on the then future commitment to purchase the remaining 30% equity interest in Kyte was to timely reflect economic events in earnings, as management’s assessment of the future purchase commitment value was driven by Kyte’s earnings or losses subsequent to the initial acquisition date and net present value at a specific point in time.
	Derivative Financial Instruments—The Company enters into derivative transactions for a variety of reasons, including managing its exposure to risk arising from changes in foreign currency, facilitating customer trading activities and, in certain instances, to engage in principal trading for the Company’s own account. Derivative assets and liabilities are carried on the Condensed Consolidated Statements of Financial Condition at fair value, with changes in the fair value recognized in the Condensed Consolidated Statements of Operations. Contracts entered into to manage risk arising from changes in foreign currency are recognized in Other income and contracts entered into to facilitate customer transactions and principal trading are recognized in Principal transactions. Derivatives are reported on a net-by-counterparty basis when management believes that a legal and enforceable right of offset exists under these agreements. See Note 14 for further information.
	Payables to Clearing Services Customers—Payables to clearing services customers include amounts due on cash and margin transactions, including futures contracts, executed on behalf of customers.
	Brokerage Transactions—The Company provides brokerage services to its clients in the form of either agency or principal transactions.
	Agency Commissions—In agency transactions, the Company charges commissions for executing transactions between buyers and sellers. Agency commission revenues and related expenses are recognized on a trade date basis.
	Principal Transactions—Principal transactions revenue is primarily derived from matched principal and principal trading transactions. Principal transactions revenues and related expenses are recognized on a trade date basis. The Company earns revenue from principal transactions on the spread between the buy and sell price of the security that is brokered. In matched principal transactions, the Company simultaneously agrees to buy instruments from one customer and sell them to another customer.
	In the normal course of its matched principal and principal trading businesses, the Company may hold security positions overnight. These positions are marked to market on a daily basis.
	Clearing Services Revenues—The Company charges fees to customers for clearing services provided for cash and derivative transactions. Clearing services revenues are recorded on a trade date basis as customer transactions occur and are presented net of any customer negotiated rebates.
	Software, Analytics and Market Data Revenue Recognition—Software revenue consists primarily of fees charged for Trayport electronic trading software, which are typically billed on a subscription basis and are recognized ratably over the term of the subscription period, which ranges from one to five years. Analytics revenue consists primarily of software license fees for Fenics® pricing tools which are typically billed on a subscription basis, and is recognized ratably over the term of the subscription period, which is generally three years. Market data revenue primarily consists of subscription fees and fees from customized one-time sales. Market data subscription fees are recognized on a straight-line basis over the term of the subscription period, which ranges from one to two years. Market data revenue from customized one-time sales is recognized upon delivery of the data.
	The Company markets its software, analytics and market data products through its direct sales force and, in some cases, indirectly through resellers. In general, the Company’s license agreements for such products do not provide for a right of return.
	Other Income—Included within Other income on the Company’s Condensed Consolidated Statements of Operations are revaluations of foreign currency derivative contracts, realized and unrealized transaction gains and losses on certain foreign currency denominated items, and gains and losses on certain investments, and interest income earned on short-term investments.
	Compensation and Employee Benefits—The Company’s compensation and employee benefits have both a fixed and variable component. Base salaries and benefit costs are primarily fixed for all employees while bonuses constitute the variable portion of compensation and employee benefits. The Company may pay certain performance bonuses in restricted stock units (“RSUs”). The Company also may grant sign-on and retention bonuses for certain newly-hired or existing employees who agree to long-term employment agreements.
	Share-Based Compensation—The Company’s share-based compensation consists of RSUs. The Company accounts for share-based compensation in accordance with ASC 718 Compensation— Stock Compensation (“ASC 718”). This accounting guidance requires measurement of compensation expense for equity-based awards at fair value and recognition of compensation expense over the service period, net of estimated forfeitures. In all periods presented, the only share-based compensation expense recognized by the Company has been RSUs. The Company determines the fair value of RSUs based on the number of units granted and the grant date fair value of the Company’s common stock, measured as of the closing price on the date of grant. See Note 10 for further information.
	Income Taxes— In accordance with ASC 740, Income Taxes (“ASC 740”), the Company provides for income taxes using the asset and liability method under which deferred income taxes are recognized for the estimated future tax effects attributable to temporary differences and carryforwards that result from events that have been recognized either in the financial statements or the income tax returns, but not both. The measurement of current and deferred income tax assets and liabilities is based on provisions of enacted tax laws. Valuation allowances are recognized if, based on the weight of available evidence, it is more likely than not that some portion of the deferred tax assets will not be realized. Management applies the more likely than not criteria prior to recognizing a financial statement benefit for a tax position taken (or expected to be taken) in a tax return. The Company recognizes interest and/or penalties related to income tax matters in interest expense and other expense, respectively.
	The Company normally determines its interim provision for or benefit from income taxes using an estimated annual effective tax rate methodology as required by ASC 740.  However, the Company has utilized a discrete period method to calculate taxes for the three and nine months ended September 30, 2013 based on actual results. The Company has determined that the calculation of an annual effective tax rate would not represent a reliable estimate due to the sensitivity of this estimated rate to minimal changes in the forecasted pre-tax income (loss) for the fourth quarter of 2013. Under the discrete method, the Company determines its provision for or benefit from income taxes based on the actual results for the nine months ended September 30, 2013 as if this interim period were an annual period.
	The decrease in the Company’s effective tax rate for the nine months ended September 30, 2013 as compared to the nine months ended September 30, 2012 was primarily due to: (i) changes in the geographic mix of profits, (ii) a tax benefit under the American Taxpayer Relief Act of 2012 related to taxes previously provided for, (iii) a tax benefit arising from a change in the Company’s view about the deductibility of a reserve previously deemed nondeductible, as a result of new information received in the first quarter of 2013, and (iv) the release of a tax liability in a foreign subsidiary where the statute of limitations has now expired.
	Treasury Stock—The Company accounts for Treasury stock using the cost method. Treasury stock held by the Company may be reissued with respect to vested RSUs in qualified jurisdictions. The Company’s policy is to account for these shares as a reduction of Treasury stock on a first-in, first-out basis.
	Foreign Currency Translation Adjustments and Transactions— Assets and liabilities of foreign subsidiaries having non-U.S. dollar functional currencies are translated at the period end rates of exchange, and revenue and expenses are translated at the average rates of exchange for the period. Gains or losses resulting from translating the foreign currency financial statements are reflected in foreign currency translation adjustments and are reported as a separate component of comprehensive income (loss) and included in accumulated other comprehensive income in the Condensed Consolidated Statement of Changes in Stockholders’ Equity. The revaluation of asset and liability balances that are denominated in currencies other than the functional currency of the business unit involved in such transactions is reflected in Other Income in the Condensed Consolidated Statements of Operations. Net gains (losses) resulting from remeasurement of foreign currency transactions and balances were $2,212 and $(1,113) for the three months ended September 30, 2013 and 2012, respectively, and $1,757 and $(3,835) for the nine months ended September 30, 2013 and 2012, respectively.
	During the three and nine months ended September 30, 2013, the Company reclassified a $1,645 foreign currency translation gain out of Accumulated other comprehensive income and into the Condensed Consolidated Statement of Operations. The amount was included within Other income and was reclassified during the current period due to the substantial liquidation of a foreign subsidiary, to which this gain was related.  The reclassification had no effect on the benefit from income taxes on the Condensed Consolidated Statement of Operations.
	Recent Accounting Pronouncements—In December 2011, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2011-11, Balance Sheet (Topic 210): Disclosures about Offsetting Assets and Liabilities (“ASU 2011-11”). ASU 2011-11 requires additional disclosure about financial instruments and derivatives instruments that are subject to netting arrangements to assist users of the financial statements in understanding the effect of those arrangements on its financial position.  In January 2013, the FASB issued an amendment to ASU 2011-11, ASU No. 2013-01 Balance Sheet (Topic 210): Clarifying the Scope of Disclosure about Offsetting Assets and Liabilities (“ASU 2013-01”).  ASU 2013-01 clarifies that the scope of ASU 2011-11 applies to derivatives accounted for in accordance with ASC 815- Derivatives and Hedging, including bifurcated embedded derivatives, repurchase agreements and reverse repurchase agreements, and securities borrowing and securities lending transaction that are either offset in accordance with Balance Sheet (Topic 210) guidance, Derivatives and Hedging (Topic 815) guidance, or subject to an enforceable master netting arrangement or similar agreement. The new disclosures were required for reporting periods beginning on or after January 1, 2013, including retrospectively for all comparative periods presented.  The adoption of ASU 2013-01 did not have a material impact on the Company’s Condensed Consolidated Financial Statements. See Note 14 for disclosures.
	In February 2013, the FASB issued ASU No. 2013-02, Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income (“ASU 2013-02”), regarding the reporting of reclassifications out of accumulated other comprehensive income. The new guidance does not change current requirements for reporting net income or other comprehensive income in financial statements. However, it requires companies to present the effects on the line items of net income of significant amounts reclassified out of accumulated other comprehensive income if the item reclassified is required to be reclassified to net income in its entirety during the same reporting period. Presentation should occur either on the face of the income statement where net income is presented or in the notes to the financial statements.  See Accounting Policy on Foreign Currency Translation Adjustments and Transactions for impact on the Condensed Consolidated Financial Statements during the three and nine months ended September 30, 2013.
	In July 2013, the FASB issued ASU No. 2013-11, Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists (“ASU 2013-11”). ASU 2013-11 requires an entity to present an unrecognized tax benefit, or a portion of an unrecognized tax benefit, in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss or tax credit carryforward, unless such tax loss or credit carryforward is not available at the reporting date under the tax law of the applicable jurisdiction to settle any additional income taxes resulting from the disallowance of a tax position. In the event that the tax position is disallowed or the tax law of the applicable jurisdiction does not require the entity to use, and the entity does not intend to use, the deferred tax asset for such purpose, the unrecognized tax benefit shall be presented in the financial statements as a liability and shall not be combined with deferred tax assets. The guidance is effective for annual reporting periods beginning after December 15, 2013, and interim periods within those annual periods, and is to be applied prospectively. The Company is currently evaluating the impact of its pending adoption of ASU 2013-11 on its Condensed Consolidated Financial Statements.

RECEIVABLES_FROM_AND_PAYABLES_

RECEIVABLES FROM AND PAYABLES TO BROKERS, DEALERS AND CLEARING ORGANIZATIONS	9 Months Ended
	Sep. 30, 2013
RECEIVABLES FROM AND PAYABLES TO BROKERS, DEALERS AND CLEARING ORGANIZATIONS	'
RECEIVABLES FROM AND PAYABLES TO BROKERS, DEALERS AND CLEARING ORGANIZATIONS	'
	3.              RECEIVABLES FROM AND PAYABLES TO BROKERS, DEALERS AND CLEARING ORGANIZATIONS
	Amounts receivable from and payable to brokers, dealers and clearing organizations consisted of the following:
		September 30,		December 31,
		2013		2012
	Receivables from brokers, dealers and clearing organizations:
	Contract value of fails to deliver	$	520,516	$	164,090
	Receivables from and deposits with clearing organizations and financial institutions	123,048		87,348
	Net pending trades	3,465		1,258
	Total	$	647,029	$	252,696
	Payables to brokers, dealers and clearing organizations:
	Contract value of fails to receive	$	486,445	$	158,256
	Payables to clearing organizations and financial institutions	26,615		6,679
	Total	$	513,060	$	164,935
	Substantially all fail to deliver and fail to receive balances at September 30, 2013 have subsequently settled at the contracted amounts.  All fail to deliver and fail to receive balances at December 31, 2012 have subsequently settled at the contracted amounts.
	In addition to the balances above, the Company had Payables to clearing services customers of $136,215 and $139,627 at September 30, 2013 and December 31, 2012, respectively. These amounts represent cash payable to the Company’s clearing customers that is held at the Company’s third-party general clearing members and are included within Cash and cash equivalents, Cash and securities segregated under federal and other regulations or Receivables from brokers, dealers and clearing organizations as follows:
		September 30,		December 31,
		2013		2012
	Cash and cash equivalents	$	—	$	27,623
	Cash segregated under federal and other regulations	60,598		47,300
	Receivables from brokers, dealers, and clearing organizations	75,617		64,704
	Total	$	136,215	$	139,627

ACQUISITIONS

ACQUISITIONS	9 Months Ended
	Sep. 30, 2013
ACQUISITIONS	'
ACQUISITIONS	'
	4.              ACQUISITIONS
	The Kyte Group Limited and Kyte Capital Management Limited
	On July 1, 2010, the Company acquired a 70% equity ownership interest in each of The Kyte Group Limited and Kyte Capital Management Limited (collectively “Kyte”). At the time of the acquisition, the Company agreed to purchase the residual 30% interest for a cash payment three years following the closing (the “Future Purchase Commitment”) with the price to be determined based on certain performance metrics for Kyte during this three year period.  During the third quarter of 2013, the Company and the selling shareholders of Kyte determined that the purchase price for the residual 30% equity interest was zero. Kyte has been included in the Condensed Consolidated Financial Statements as a wholly-owned subsidiary since the acquisition date, with a liability recorded for the Future Purchase Commitment. Subsequent changes in the fair value of the Future Purchase Commitment were recorded in Other income in the Condensed Consolidated Statements of Operations.
	Included as part of the initial purchase price was £5,000 (or approximately $7,592) that was deposited into an escrow account with a third-party escrow agent and 1,339,158 contingently issuable shares of the Company’s common stock. The Company was also required to pay an additional cash amount to the selling shareholders of Kyte equal to the total cash dividends the selling shareholders would have received if the 1,339,158 contingently issuable shares had been outstanding as of the initial purchase date of July 1, 2010. The escrow funds, additional cash payment and contingently issuable shares were paid and issued to the selling shareholders of Kyte during the third quarter of 2013 in connection with the final determination of the Future Purchase Commitment and the waiver of certain conditions relating to one of Kyte’s investments in a third party.

GOODWILL_AND_INTANGIBLE_ASSETS

GOODWILL AND INTANGIBLE ASSETS	9 Months Ended
	Sep. 30, 2013
GOODWILL AND INTANGIBLE ASSETS	'
GOODWILL AND INTANGIBLE ASSETS	'
	5.              GOODWILL AND INTANGIBLE ASSETS
	Goodwill—Changes in the carrying amount of the Company’s goodwill for the nine months ended September 30, 2013 were as follows:
		December 31,		Goodwill		Foreign currency			September 30,
		2012		Acquired		translation			2013
	Goodwill
	Americas Brokerage	$	83,289	$	—	$	—		$	83,289
	EMEA Brokerage	14,397		—		(48		)	14,349
	Asia Brokerage	—		—		—			—
	Clearing and Backed Trading	41,600		—		(158		)	41,442
	All Other	128,691		—		—			128,691
		$	267,977	$	—	$	(206	)	$	267,771
	Goodwill is required to be tested for impairment at least annually and more frequently when indicators of impairment exist. All of the Company’s goodwill is allocated to its reporting units and the goodwill impairment tests are performed at the reporting unit level. The Company determined Americas Brokerage, EMEA Brokerage, Asia Brokerage, Clearing and Backed Trading, Trayport, and Fenics to be its reporting units. Based on the results of the most recent annual impairment tests performed as of November 1, 2012, no goodwill impairment was recognized during the year ended December 31, 2012. Subsequent to December 31, 2012, no events or changes in circumstances occurred which would indicate any goodwill impairment.
	Intangible Assets—Intangible assets consisted of the following:
		September 30, 2013							December 31, 2012
		Gross		Accumulated		Net			Gross		Accumulated		Net
		amount		amortization		carrying			amount		amortization		carrying
				and foreign		value					and foreign		value
				currency							currency
				translation							translation
	Intangible assets
	Customer relationships	$	78,896	$	41,492	$	37,404		$	77,426	$	35,597	$	41,829
	Trade names	8,951		6,565		2,386			8,951		6,181		2,770
	Core technology	6,400		6,400		—			6,400		5,835		565
	Non-compete agreements	4,204		3,806		398			3,874		3,656		218
	Favorable lease agreements	620		560		60			620		500		120
	Patents	3,131		1,097		2,034			3,131		723		2,408
	Other	647		257		390			647		65		582
	Total	$	102,849	$	60,177	$	42,672		$	101,049	$	52,557	$	48,492
	Intangible amortization expense for the three months ended September 30, 2013 and 2012 was $2,339 and $2,922, respectively. Intangible amortization expense for the nine months ended September 30, 2013 and 2012 was $7,308 and $8,762, respectively.
	At September 30, 2013, expected amortization expense for intangible assets is as follows:
	2013 (remaining three months)	$	2,267
	2014	9,015
	2015	8,909
	2016	6,878
	2017	3,494
	Thereafter	12,109
	Total	$	42,672

OTHER_ASSETS_AND_OTHER_LIABILI

OTHER ASSETS AND OTHER LIABILITIES	9 Months Ended
	Sep. 30, 2013
OTHER ASSETS AND OTHER LIABILITIES	'
OTHER ASSETS AND OTHER LIABILITIES	'
	6.              OTHER ASSETS AND OTHERLIABILITIES
	Other assets consisted of the following:
		September 30,		December 31,
		2013		2012
	Deferred tax assets	$	51,046	$	41,567
	Investments accounted for under the cost method and equity method	42,121		31,414
	Forgivable employee loans and advances to employees	26,009		31,655
	Prepaid bonuses	25,833		31,847
	Deferred financing fees	6,942		8,074
	Financial instruments owned	2,981		25,250
	Software inventory, net	2,905		4,615
	Other	28,726		28,774
	Total Other assets	$	186,563	$	203,196
	Other liabilities consisted of the following:
		September 30,		December 31,
		2013		2012
	Payroll related liabilities	$	27,685	$	15,418
	Deferred revenues	9,251		7,247
	Unrecognized tax benefits	8,956		8,957
	Deferred tax liabilities	6,715		7,943
	Financial instruments sold, not yet purchased	1,567		1,481
	Future purchase commitment and contingent consideration liabilities	100		3,727
	Other	31,237		38,801
	Total Other liabilities	$	85,511	$	83,574

SHORTTERM_BORROWINGS_AND_LONGT

SHORT-TERM BORROWINGS AND LONG-TERM OBLIGATIONS	9 Months Ended
	Sep. 30, 2013
SHORT-TERM BORROWINGS AND LONG-TERM OBLIGATIONS	'
SHORT-TERM BORROWINGS AND LONG-TERM OBLIGATIONS	'
	7.              SHORT-TERM BORROWINGS ANDLONG-TERM OBLIGATIONS
	The Company’s outstanding debt obligations consisted of the following:
		September 30,		December 31,
		2013		2012
	8.375% Senior Notes due 2018	$	240,000	$	250,000
	Loans pursuant to Credit Agreement	10,000		—
	Total	$	250,000	$	250,000
	The Company’s debt obligations are carried at historical amounts. The fair value of the Company’s Long-term obligations, categorized within Level 2 of the fair value hierarchy, is measured primarily using pricing service data from external providers. The carrying amounts and estimated fair values of the Company’s Long-term obligations were as follows:
		September 30, 2013				December 31, 2012
		Carrying		Fair Value		Carrying		Fair Value
		Amount				Amount
	8.375% Senior Notes	$	240,000	$	242,700	$	250,000	$	220,720
	8.375% Senior Notes
	In July 2011, the Company issued $250,000 in aggregate principal amount of 8.375% Senior Notes (the “8.375% Senior Notes”) due 2018 in a private offering (the “Offering”) to qualified institutional buyers pursuant to Rule 144A and to certain persons in offshore transactions pursuant to Regulation S, each under the Securities Act of 1933, as amended (the “Securities Act”). The notes were priced to investors at 100% of their principal amount, and mature in July 2018. Interest on these notes is payable semi-annually in arrears on the 19th of January and July. Transaction costs of approximately $9,100 related to the 8.375% Senior Notes were deferred and are being amortized over the term of the notes. On December 21, 2011, the Company completed an exchange offer for the 8.375% Senior Notes whereby it exchanged $250,000 in aggregate principal amount of the 8.375% Senior Notes for 8.375% Senior Notes that are registered under the Securities Act.
	On January 18, 2013, Moody’s Investor Services lowered its credit rating on the Company’s 8.375% Senior Notes two notches to B1, which increased the Company’s applicable per annum interest, effective January 19, 2013, by an additional 50 basis points.  On April 19, 2013, Fitch Ratings, Inc. (“Fitch”) further lowered its credit rating on the Company’s 8.375% Senior Notes two notches to BB and revised its outlook from Stable to Negative. This credit rating downgrade by Fitch increased our applicable per annum interest by an additional 50 basis points, effective July 19, 2013.  On June 26, 2013, Standard & Poor’s (“S&P”) further lowered its credit rating on the Company’s 8.375% Senior Notes one notch to B+ and revised its outlook from Negative to Stable. This credit rating downgrade by S&P increased the Company’s applicable per annum interest by an additional 25 basis points, effective July 19, 2013.
	The cumulative effect of all such downgrades to the Company’s credit rating by the various rating agencies subsequent to the issuance of our 8.375% Senior Notes resulted in 200 basis points penalty interest, which is the maximum increase permitted under the indenture. The additional 200 basis points of interest equates to $4,800 in additional interest expense per annum, based on the aggregate amount of outstanding principal as of September 30, 2013.
	In March 2013, the Company repurchased $10,000 principal amount of its 8.375% Senior Notes on the open market for an aggregate purchase price of $9,602, including accrued interest and sales commissions. The Company funded the repurchase of these notes with borrowings under its Credit Agreement.
	At September 30, 2013 and December 31, 2012, unamortized deferred financing fees related to the 8.375% Senior Notes of $5,981 and $7,205, respectively, were recorded within Other assets and the Company was in compliance with all applicable covenants.
	Credit Agreement
	In March 2013, the Company entered into an amendment to its second amended and restated credit agreement (as amended, the “Credit Agreement”) with Bank of America, N.A. and certain other lenders. The Credit Agreement provides for maximum revolving loans of up to $75,000 until December 2013, at which time $18,750 of the lender commitments mature. The remaining $56,250 of lender commitments matures in December 2015. The Credit Agreement provides for up to $50,000 for letters of credit.
	At December 31, 2012, the Credit Agreement provided for maximum revolving loans of up to $129,500, with $50,000 for letters of credit.
	Revolving loans may be either base rate loans or Eurocurrency rate loans. Eurocurrency rate loans bear interest at the annualized rate of one-month LIBOR plus the application margin and base rate loans bear interest at a rate per annum equal to a prime rate plus the applicable margin. Letter of credit fees per annum are equal to the applicable margin times the outstanding amount drawn under such letter of credit. As long as no default has occurred under the Credit Agreement, the applicable margin for base rate and Eurocurrency rate loans and letters of credit is based on a matrix that varies with a ratio of outstanding debt to EBITDA, as defined in the Credit Agreement.
	The weighted average interest rate of the outstanding loans under the Credit Agreement was 3.43% at September 30, 2013.  At September 30, 2013 and December 31, 2012, unamortized deferred financing fees related to the Credit Agreement were $961 and $869, respectively.
	The Credit Agreement contains certain financial and other covenants. The Company was in compliance with all applicable covenants at September 30, 2013 and December 31, 2012.

STOCKHOLDERS_EQUITY

STOCKHOLDERS' EQUITY	9 Months Ended
	Sep. 30, 2013
STOCKHOLDERS' EQUITY	'
STOCKHOLDERS' EQUITY	'
	8.              STOCKHOLDERS’EQUITY
	In August 2007, the Company’s Board of Directors authorized the Company to implement a stock repurchase program to repurchase a limited number of shares of the Company’s common stock. Under the repurchase plan, the Board of Directors authorized the Company to repurchase shares of the Company’s common stock on the open market in such amounts as determined by the Company’s management, provided, however, such amounts are not to exceed, during any calendar year, the number of shares issued upon the exercise of stock options plus the number of shares underlying grants of RSUs that are granted or which management reasonably anticipates will be granted in such calendar year. During the three and nine months ended September 30, 2013, the Company did not repurchase any shares of its common stock. During the three months ended September 30, 2012, the Company repurchased 1,413,067 shares of its common stock on the open market at an average price of $3.25 per share for a total cost of $4,641, including sales commissions. During the nine months ended September 30, 2012, the Company repurchased 3,107,469 shares of its common stock on the open market at an average price of $3.17 per share for a total cost of $9,939, including sales commissions. These repurchased shares were recorded at cost as Treasury stock in the Condensed Consolidated Statements of Financial Condition.
	On May 31, and August 30, 2013, the Company paid a cash dividend of $0.05 per share, which, based upon the number of shares outstanding on the record date for such dividends, totaled $5,999 and $6,096, respectively. In December 2012, the Company’s Board of Directors declared a dividend for the fourth quarter of 2012 on an accelerated basis. The dividend was declared and paid in December 2012 and the Company, therefore, did not pay a cash dividend during the first quarter of 2013. On each of March 30, May 31, and August 31, 2012, the Company paid a cash dividend of $0.05 per share, which, based upon the number of shares outstanding on the record date for such dividends, totaled $5,897, $5,991, and $5,873, respectively.

LOSS_EARNINGS_PER_SHARE

(LOSS) EARNINGS PER SHARE	9 Months Ended
	Sep. 30, 2013
(LOSS) EARNINGS PER SHARE	'
(LOSS) EARNINGS PER SHARE	'
	9.              (LOSS) EARNINGS PER SHARE
	Basic (loss) earnings per share for common stock is calculated by dividing net (loss) income available to common stockholders by the weighted average number of shares of common stock outstanding during the period. Diluted (loss) earnings per share is calculated by dividing net (loss) income by the sum of: (i) the weighted average number of shares outstanding, (ii) outstanding stock options and RSUs (using the “treasury stock” method when the impact of such options and RSUs would be dilutive), and (iii) any contingently issuable shares, when dilutive.
	Basic and diluted (loss) earnings per share for the three and nine months ended September 30, 2013 and 2012 were as follows:
		Three Months Ended September 30,						Nine Months Ended September 30,
		2013			2012			2013		2012
	Basic (loss) earnings per share
	GFI’s net (loss) income	$	(461	)	$	(8,693	)	$	10,904	$	1,419
	Weighted average common shares outstanding	120,331,179			115,541,373			118,138,756		116,073,488
	Basic (loss) earnings per share	$	(0.00	)	$	(0.08	)	$	0.09	$	0.01
	Diluted (loss) earnings per share
	GFI’s net (loss) income	$	(461	)	$	(8,693	)	$	10,904	$	1,419
	Weighted average common shares outstanding	120,331,179			115,541,373			118,138,756		116,073,488
	Effect of dilutive options, RSUs, and other contingently issuable shares	—			—			8,719,703		7,496,622
	Weighted average shares outstanding and common stock equivalents	120,331,179			115,541,373			126,858,459		123,570,110
	Diluted (loss) earnings per share	$	(0.00	)	$	(0.08	)	$	0.09	$	0.01
	Excluded from the computation of diluted (loss) earnings per share because their effect would be anti-dilutive were the following: (i) 259,380 RSUs and 69,476 stock options for the three months ended September 30, 2013 and (ii) 7,341,891 RSUs and 77,476 stock options for the three months ended September 30, 2012, (iii) 2,660,905 RSUs and 69,476 options for the nine months ended September 30, 2013 and (iv) 8,433,605 RSUs and 77,476 options for the nine months ended September 30, 2012.
	Included in the computation of diluted earnings per share, but not in the computation of basic earnings per share as the conditions for issuance were not satisfied as of the respective reporting period were 2,736,121 and 3,682,916 contingently issuable shares for the nine months ended September 30, 2013 and 2012, respectively.
	As a result of the net loss for the three months ended September 30, 2013, the following were excluded from the computation of diluted loss per share for that period: common shares underlying options to purchase 99,362 shares of common stock, 6,320,799 RSUs, and 1,637,673 shares that were contingently issuable.  As a result of the net loss for the three months ended September 30, 2012, the following were excluded from the computation of diluted loss per share for that period: common shares underlying options to purchase 39,715 shares of common stock, 3,130,644 RSUs, and 3,682,916 shares that were contingently issuable.

SHAREBASED_COMPENSATION

SHARE-BASED COMPENSATION	9 Months Ended
	Sep. 30, 2013
SHARE-BASED COMPENSATION	'
SHARE-BASED COMPENSATION	'
	10.       SHARE-BASED COMPENSATION
	The Company issues RSUs to its employees under the Amended and Restated GFI Group Inc. 2008 Equity Incentive Plan, which was approved by the Company’s stockholders on June 6, 2013 (as amended and restated, the “2008 Equity Incentive Plan”). Prior to the initial approval of the 2008 Equity Incentive Plan, the Company issued RSUs under the GFI Group Inc. 2004 Equity Incentive Plan (the “2004 Equity Incentive Plan”).
	The 2008 Equity Incentive Plan permits the grant of non-qualified stock options, incentive stock options, stock appreciation rights, shares of restricted stock, restricted stock units and performance units to employees, non-employee directors or consultants. The Company issues shares from authorized but unissued shares and authorized and issued shares reacquired and held as treasury shares, which are reserved for issuance upon the vesting of RSUs granted pursuant to the 2008 Equity Incentive Plan. As of September 30, 2013, there were 8,579,962 shares of common stock available for future grants of awards under this plan. The fair value of RSUs is based on the closing price of the Company’s common stock on the date of grant and is recorded as compensation expense over the service period, net of estimated forfeitures.
	The following is a summary of the Company’s RSU activity during the nine months ended September 30, 2013:
		RSUs		Weighted-
				Average
				Grant Date
				Fair Value
	Outstanding December 31, 2012	19,353,382		$	4.27
	Granted	6,554,167		3.71
	Vested	(6,338,258	)	4.48
	Cancelled	(885,739	)	4.01
	Outstanding September 30, 2013	18,683,552		$	4.02
	The weighted average grant-date fair value of RSUs granted for the nine months ended September 30, 2013 was $3.71 per unit, compared with $3.56 per unit for the same period in the prior year. Total compensation expense and related income tax benefits recognized in relation to RSUs are as follows:
		Three Months Ended September 30,						Nine Months Ended September 30,
		2013			2012			2013			2012
	Compensation expense	$	6,870		$	7,751		$	22,372		$	24,653
	Income tax benefits	$	1,913		$	2,359		$	6,655		$	7,506
	At September 30, 2013, total unrecognized compensation cost related to RSUs, prior to the consideration of expected forfeitures, was approximately $56,057 and is expected to be recognized over a weighted-average period of 1.71 years. The total fair value of RSUs vested during the nine months ended September 30, 2013 and 2012 was $28,395 and $30,021, respectively.
	As of September 30, 2013, the Company had stock options outstanding under two plans: the GFI Group 2002 Stock Option Plan (the “GFI Group 2002 Plan”) and the GFInet Inc. 2000 Stock Option Plan (the “GFInet 2000 Plan”). No additional grants will be made under these plans. Under each plan: options were granted to employees, non-employee directors or consultants to the Company; both incentive and non-qualified stock options were available for grant; options were issued with terms up to ten years from date of grant; and options were generally issued with an exercise price equal to or greater than the fair market value at the time the option was granted. Under both plans, the options became exercisable upon the completion of the Company’s initial public offering, which occurred in January 2005. Options outstanding under both plans are exercisable for shares of the Company’s common stock. The Company issues shares from the authorized but unissued shares reserved for issuance under the GFI Group 2002 Plan or the GFInet 2000 Plan, respectively, upon the exercise of options under such plans.
	The following is a summary of stock options outstanding under both the GFI Group 2002 Plan and the GFInet 2000 Plan as of September 30, 2013:
		GFI Group 2002 Plan					GFInet 2000 Plan
		Options		Weighted			Options		Weighted
				Average					Average
				Exercise					Exercise
				Price					Price
	Outstanding December 31, 2012	575,220		$	3.29		16,844		$	2.97
	Exercised	(205,952	)	2.97			(16,844	)	2.97
	Cancelled	(10,104	)	2.97			—		—
	Expired	(3,156	)	4.78			—		—
	Outstanding September 30, 2013	356,008		$	3.42		—		$	—
	As of September 30, 2013 and 2012, there was no unrecognized compensation cost related to stock options.

COMMITMENTS_AND_CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2013
COMMITMENTS AND CONTINGENCIES	'
COMMITMENTS AND CONTINGENCIES	'
	11.       COMMITMENTS AND CONTINGENCIES
	Purchase Obligations—The Company has various unconditional purchase obligations. These obligations are for the purchase of market data from a number of information service providers during the normal course of business. As of September 30, 2013, the Company had total purchase commitments for market data of approximately $24,801 with $18,369 due within the next twelve months, $6,278 due between one to three years and $154 due between three to five years. Additionally, the Company had other purchase commitments of $6,634, primarily related to network implementations in the U.S. and U.K., and $1,126 for hosting and software license agreements. Of these other purchase commitments, approximately $5,397 is due within the next twelve months.
	Contingencies—In the normal course of business, the Company and certain subsidiaries included in the condensed consolidated financial statements are, and have been in the past, involved in various lawsuits and proceedings and are, and have been in the past, involved in certain regulatory examinations. These legal proceedings are at varying stages of adjudication, arbitration or investigation and involve a wide variety of claims. In view of the inherent difficulty of predicting the outcome of such litigation and regulatory matters, particularly where the claimants seek very large or indeterminate damages or where the matters present novel legal theories, the Company generally cannot predict what the eventual outcome of the pending matters will be, what the timing of the ultimate resolution of these matters will be, or what the eventual loss, fines or penalties, if any, relating to each matter may be.
	The Company is subject to the possibility of losses from these various contingencies. Considerable judgment is necessary to estimate the probability and amount of any loss from such contingencies. In accordance with applicable accounting guidelines, an accrual is made when it is probable that a liability has been incurred or an asset has been impaired and the amount of loss can be reasonably estimated. Where a loss contingency is not both probable and estimable, the Company does not establish an accrued liability.
	The Company is subject to regular examinations by various tax authorities in jurisdictions in which the Company has significant business operations. The Company regularly assesses the likelihood of additional tax assessments that may result from these examinations in each of the tax jurisdictions. A tax accrual has been established, which the Company believes to be adequate in relation to the potential for additional tax assessments. Once established, the accrual may be adjusted based on new information or events. The imposition of additional tax assessments, penalties or fines by a tax authority could have a material impact on the Company’s effective tax rate.
	Additionally, the Company has recorded reserves for certain contingencies to which it may have exposure, such as contingencies related to the employer portion of National Insurance Contributions in the U.K.
	Based on currently available information, the outcome of the Company’s outstanding legal proceedings are not expected to have a material adverse impact on the Company’s financial position. However, the outcome of any such matters may be material to the Company’s results of operations or cash flows in a given period. It is not presently possible to determine the Company’s ultimate exposure to these matters and there is no assurance that the resolution of the Company’s outstanding matters will not significantly exceed any reserves accrued by the Company.
	Risks and Uncertainties—The Company primarily generates its revenues by executing and facilitating transactions for counterparties. Revenues for these services are transaction based. As a result, the Company’s revenues will likely vary based upon the trading volumes of the various securities, commodities, foreign exchange and other cash and derivative markets in which the Company provides its services.
	Guarantees—The Company, through its subsidiaries, is a member of certain exchanges and clearing houses. Under the membership agreements, members are generally required to guarantee certain obligations. To mitigate the performance risks of its members, the exchanges and clearing houses may, from time to time, require members to post collateral, as well as meet certain minimum financial standards. The Company’s maximum potential liability under these arrangements cannot be quantified. However, management believes that the potential for the Company to be required to make payments under these arrangements is unlikely. Accordingly, no contingent liability is recorded in the Condensed Consolidated Statements of Financial Condition for these arrangements.

MARKET_AND_CREDIT_RISKS

MARKET AND CREDIT RISKS	9 Months Ended
	Sep. 30, 2013
MARKET AND CREDIT RISKS	'
MARKET AND CREDIT RISKS	'
	12.       MARKET AND CREDIT RISKS
	Disclosure regarding the Company’s financial instruments with market and credit risks are described in “Note 15—Market and Credit Risks” of the Notes to the Consolidated Financial Statements contained in the Company’s 2012 Form 10-K. There have been no material changes to these risks during the nine months ended September 30, 2013.

FAIR_VALUE_OF_FINANCIAL_INSTRU

FAIR VALUE OF FINANCIAL INSTRUMENTS	9 Months Ended
	Sep. 30, 2013
FAIR VALUE OF FINANCIAL INSTRUMENTS	'
FAIR VALUE OF FINANCIAL INSTRUMENTS	'
	13.       FAIR VALUE OF FINANCIAL INSTRUMENTS
	Certain of the Company’s assets and liabilities are carried at fair value or contracted amounts that approximate fair value. Assets and liabilities that are recorded at contracted amounts approximating fair value consist primarily of receivables from and payables to brokers, dealers and clearing organizations and payables to clearing services customers. These receivables and payables to brokers, dealers and clearing organizations are short-term in nature, and following September 30, 2013, substantially all have settled at the contracted amounts. The Company’s marketable equity securities, included in Other assets, are recorded at fair value based on their quoted market price. The Company’s investments that are accounted for under the cost and equity methods are investments in companies that are not publicly traded and for which no established market for their securities exists. The fair value of these investments is only estimated if there are identified events or changes in circumstances that may have a significant adverse effect on the carrying value of the investment.
	The Company’s financial assets and liabilities recorded at fair value have been categorized based upon a fair value hierarchy in accordance with ASC 820-10. In accordance with ASC 820-10, the Company has categorized its financial assets and liabilities, based on the priority of the inputs to the valuation technique, into a three-level fair value hierarchy as set forth below.
	Level 1—Financial assets and liabilities whose values are based on unadjusted quoted prices for identifiable assets or liabilities in an active market that the company has the ability to access at the measurement date (examples include active exchange-traded equity securities, listed derivatives, and most U.S. Government and agency securities).
	Level 2—Financial assets and liabilities whose values are based on quoted prices in markets where trading occurs infrequently or whose values are based on quoted prices of instruments with similar attributes in active markets. Level 2 inputs include the following:
	·                  Quoted prices for identifiable or similar assets or liabilities in non-active markets (examples include corporate and municipal bonds which trade infrequently); and
	·                  Inputs other than quoted prices that are observable for substantially the full term of the asset or liability (examples include interest rate and currency swaps).
	Level 3—Financial assets and liabilities whose values are based on prices or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement. These inputs reflect management’s own assumptions about the assumptions a market participant would use in pricing the asset or liability.
	Valuation Techniques
	A description of the valuation techniques applied to the Company’s major categories of assets and liabilities measured at fair value on a recurring basis are as follows:
	U.S. Treasury Securities - U.S. Treasury securities are valued using quoted market prices. Valuation adjustments are not applied. Accordingly, U.S. Treasury securities are generally categorized in Level 1 of the fair value hierarchy.
	Equity Securities - Equity securities include mostly exchange-traded securities and are valued based on quoted market prices. Accordingly, exchange-traded equity securities are generally categorized in Level 1 of the fair value hierarchy.  Non-exchange traded equity securities are measured primarily using broker quotations, pricing service data from external providers and prices observed for recently executed market transactions. Non-exchange traded equity securities are generally categorized within Level 2 of the fair value hierarchy.
	Corporate Bonds — Corporate bonds are measured primarily using broker quotations, pricing service data from external providers and prices observed for recently executed market transactions. Corporate bonds are generally categorized in Level 2 of the fair value hierarchy.
	Foreign Government Bonds — Foreign government bonds are mostly valued using quoted market prices. Accordingly, foreign government bonds are generally categorized in Level 1 of the fair value hierarchy.
	Derivative Contracts — Derivative contracts include instruments such as foreign exchange, commodity, fixed income and equity derivative contracts.
	Listed Derivative Contracts - Listed derivatives that are actively traded are valued based on quoted prices from the exchange and are categorized in Level 1 of the fair value hierarchy.
	OTC Derivative Contracts - OTC derivative contracts include forwards, swaps, and options contracts related to foreign currencies. Depending on the product and the terms of the transaction, the fair value of OTC derivative products can be either observed or modeled using a series of techniques and model inputs from comparable benchmarks, including closed-form analytic formulas, such as the Black-Scholes option-pricing model, and simulation models or a combination thereof.  Many pricing models do not entail material subjectivity because the methodologies employed do not necessitate significant judgment, and the pricing inputs are observed from actively quoted markets. In the case of more established derivative products, the pricing models used by the Company are widely accepted by the financial services industry. OTC derivative products valued by the Company using pricing models generally fall into this category and are categorized in Level 2 of the fair value hierarchy.
	Equity warrants - Non-exchange traded equity warrants are classified within Level 3 of the fair value hierarchy and are measured using the Black-Scholes model with key inputs impacting the valuation including the underlying security price, implied volatility, dividend yield, interest rate curve, strike price and maturity date.
	Convertible Note Receivable, Available-For-Sale — During the fourth quarter of 2011, the Company exchanged its membership interest in a third party brokerage firm for a convertible senior secured promissory note in that company. This security was previously measured using valuation techniques involving quoted prices of or market data for comparable companies, including credit ratings, peer company ratios and discounted cash flow analyses. As the inputs used in estimating the fair value of this convertible debt security were both unobservable and significant to the overall fair value measurement of this asset, the asset was categorized within Level 3 of the fair value hierarchy. During the three months ended September 30, 2012, the third party brokerage firm notified the Company that they had immediate liquidity concerns and that there was the prospect of insolvency in the near future.  Based upon this information, the Company determined its estimated fair value of the convertible senior secured promissory note to be zero.
	Future Purchase Commitment - In connection with the acquisition of 70% of the equity ownership interests in Kyte, the Company agreed to purchase the residual 30% equity interest in Kyte. The purchase price for the residual 30% equity interest was determined to be zero in the third quarter of 2013.  Beginning with the initial acquisition date, up until the final settlement of the Future Purchase Commitment during the third quarter of 2013, an estimate of the payment for the residual 30% interest was determined pursuant to a formula based on Kyte’s forecasted and actual earnings and losses. The inputs used in estimating the fair value of this Future Purchase Commitment were both unobservable and significant to the overall fair value measurement of this liability. Therefore, the liability was categorized in Level 3 of the fair value hierarchy.
	Contingent Consideration —The category consists primarily of contingent consideration related to the acquisition of a retail energy brokerage business, completed on November 1, 2009. This contingent liability is remeasured at fair value and is based on estimated future collections of accounts receivable through the first quarter of 2014 related to the earnings of the acquired business through October 31, 2013.
	The inputs used in estimating the fair value of this contingent consideration are both unobservable and significant to the overall fair value measurement of this liability, therefore the liability is categorized in Level 3 of the fair value hierarchy.
	In the three and nine months ended September 30, 2013 and 2012, respectively, the Company did not have any material transfers among Level 1, Level 2, and Level 3.
	Financial Assets and Liabilities measured at fair value on a recurring basis as of September 30, 2013 are as follows:
		Quoted Prices in			Significant Other			Significant			Balance at
		Active Markets for			Observable			Unobservable			September 30,
		Identical Assets			Inputs			Inputs			2013
		(Level 1)			(Level 2)			(Level 3)
	Assets
	Other assets: Financial instruments owned:
	Equity securities	$	2,521		$	177		$	—		$	2,698
	Derivative contracts:
	Foreign exchange derivative contracts	$	4		$	20,685		$	—		$	20,689
	Fixed income derivative contracts	1,208			—			—			1,208
	Equity derivative contracts	—			—			14			14
	Commodity derivative contracts	—			—			—			—
	Netting (1)	(1,212		)	(20,416		)	—			(21,628		)
	Total derivative contracts	$	—		$	269		$	14		$	283
	Total financial instruments owned	$	2,521		$	446		$	14		$	2,981
	Other assets: Other:
	Equity security, available-for-sale	$	4,354		$	—		$	—		$	4,354
	Total	$	6,875		$	446		$	14		$	7,335
	Liabilities
	Other liabilities: Financial instruments sold, not yet purchased:
	Equity securities	$	24		$	—		$	—		$	24
	Foreign government bonds	68			—			—			68
	Derivative contracts:
	Foreign exchange derivative contracts	$	91		$	21,406		$	—		$	21,497
	Fixed income derivative contracts	1,606			—			—			1,606
	Equity derivative contracts	—			—			—			—
	Commodity derivative contracts	—			—			—			—
	Netting (1)	(1,212		)	(20,416		)	—			(21,628		)
	Total derivative contracts	$	485		$	990		$	—		$	1,475
	Total financial instruments sold, not yet purchased	$	577		$	990		$	—		$	1,567
	Other liabilities: Future purchase commitment	$	—		$	—		$	—		$	—
	Other liabilities: Contingent consideration	$	—		$	—		$	100		$	100
	Total	$	577		$	990		$	100		$	1,667
	(1)         Represents the impact of netting on a net-by-counterparty basis.
	Excluded from the table above is initial and variation margin on net short derivative contracts related to exchange traded futures in the amount of $877. These amounts were included within Receivables from brokers, dealers and clearing organizations.
	Financial Assets and Liabilities measured at fair value on a recurring basis as of December 31, 2012 are as follows:
		Quoted Prices in			Significant Other			Significant			Balance at
		Active Markets for			Observable			Unobservable			December 31,
		Identical Assets			Inputs			Inputs			2012
(Level 1)		(Level 2)			(Level 3)
Assets
Other assets: Financial instruments owned:
Equity securities	$	1,223		$	199		$	—		$	1,422
Derivative contracts:
Foreign exchange derivative contracts	$	—		$	182,343		$	—		$	182,343
Fixed income derivative contracts	394			—			—			394
Equity derivative contracts	40,578			—			28			40,606
Commodity derivative contracts	—			1,401			—			1,401
Netting (1)	(17,961		)	(182,955		)	—			(200,916		)
Total derivative contracts	$	23,011		$	789		$	28		$	23,828
Total financial instruments owned	$	24,234		$	988		$	28		$	25,250
Other assets: Other:
Equity security, available-for-sale	$	3,356		$	—		$	—		$	3,356
Convertible note receivable, available-for-sale	—			—			—			—
Total	$	27,590		$	988		$	28		$	28,606
Liabilities
Other liabilities: Financial instruments sold, not yet purchased:
Equity securities	$	205		$	—		$	—		$	205
Derivative contracts:
Foreign exchange derivative contracts	$	14		$	182,573		$	—		$	182,587
Fixed income derivative contracts	595			—			—			595
Equity derivative contracts	17,567			—			—			17,567
Commodity derivative contracts	—			1,400			—			1,400
Netting (1)	(17,961		)	(182,912		)	—			(200,873		)
Total derivative contracts	$	215		$	1,061		$	—		$	1,276
Total financial instruments sold, not yet purchased	$	420		$	1,061		$	—		$	1,481
Other liabilities: Future purchase commitment	$	—		$	—		$	3,209		$	3,209
Other liabilities: Contingent consideration	$	—		$	—		$	518		$	518
Total	$	420		$	1,061		$	3,727		$	5,208
(1)         Represents the impact of netting on a net-by-counterparty basis.
Excluded from the table above is initial and variation margin on net long derivative contracts related to exchange traded futures in the amount of $49 and net short derivative contracts related to exchange traded futures in the amount of $14,986. These amounts were included within Receivables from brokers, dealers and clearing organizations.
Changes in Level 3 Financial Assets and Liabilities measured at fair value on a recurring basis for the three months ended September 30, 2013 are as follows:
	Beginning			Total realized			Unrealized gains			Purchases			Issuances		Sales		Settlements			Ending		Unrealized gains
	Balance			and unrealized			(losses) included													Balance at		(losses) for Level
				gains (losses)			in Other													September 30,		3 Assets /
				included in			comprehensive													2013		Liabilities
				Income (1)			(income) loss															Outstanding at
																						September 30,
																						2013
Assets
Other assets:
Financial instruments owned:
Equity derivative contracts	$	14		$	—		$	—		$	—		$	—	$	—	$	—		$	14	$	—
Liabilities
Other liabilities:
Future purchase commitment	$	798		$	—		$	—		$	—		$	—	$	—	$	(798	)	$	—	$	—
Other liabilities:
Contingent consideration	$	204		$	(55	)	$	—		$	—		$	—	$	—	$	(159	)	$	100	$	(55	)
(1)                   Realized and unrealized gains (losses) are reported in Other income in the Consolidated Statements of Operations.
Changes in Level 3 Financial Assets and Liabilities measured at fair value on a recurring basis for the three months ended September 30, 2012 are as follows:
	Beginning			Total realized			Unrealized gains			Purchases			Issuances		Sales		Settlements			Ending		Unrealized gains
	Balance			and unrealized			(losses) included													Balance at		(losses) for Level
				gains (losses)			in Other													September 30,		3 Assets /
				included in			comprehensive													2012		Liabilities
				Income (1)			(income) loss															Outstanding at
																						September 30,
																						2012
Assets
Other assets:
Financial instruments owned:
Equity derivative contracts	$	2,375		$	(1,709	)	$	—		$	—		$	—	$	—	$	—		$	666	$	(1,709	)
Other:
Convertible note receivable, available-for-sale	$	2,662		$	(2,662	)	$	—		$	—		$	—	$	—	$	—		$	—	$	(2,662	)
Liabilities
Other liabilities:
Future purchase commitment	$	5,600		$	2,081		$	(125	)	$	—		$	—	$	—	$	—		$	3,644	$	2,081
Other liabilities:
Contingent consideration	$	777		$	(168	)	$	—		$	—		$	—	$	—	$	(136	)	$	809	$	(168	)
(1)                                     Realized and unrealized gains (losses) are reported in Other income in the Condensed Consolidated Statements of Operations.
Changes in Level 3 Financial Assets and Liabilities measured at fair value on a recurring basis for the nine months ended September 30, 2013 are as follows:
	Beginning			Total realized			Unrealized gains			Purchases			Issuances		Sales		Settlements			Ending		Unrealized gains
	Balance			and unrealized			(losses) included													Balance at		(losses) for Level
				gains (losses)			in Other													September 30,		3 Assets /
				included in			comprehensive													2013		Liabilities
				Income (1)			(income) loss															Outstanding at
																						September 30,
																						2013
Assets
Other assets:
Financial instruments owned:
Equity derivative contracts	$	28		$	(14	)	$	—		$	—		$	—	$	—	$	—		$	14	$	(14	)
Liabilities
Other liabilities:
Future purchase commitment	$	3,209		$	2,203		$	208		$	—		$	—	$	—	$	(798	)	$	—	$	—
Other liabilities:
Contingent consideration	$	518		$	(55	)	$	—		$	—		$	—	$	—	$	(473	)	$	100	$	(55	)
(1)                                     Realized and unrealized gains (losses) are reported in Other income in the Consolidated Statements of Operations.
Changes in Level 3 Financial Assets and Liabilities measured at fair value on a recurring basis for the nine months ended September 30, 2012 are as follows:
	Beginning			Total realized			Unrealized gains			Purchases			Issuances		Sales		Settlements			Ending		Unrealized gains
	Balance			and unrealized			(losses) included													Balance at		(losses) for Level
				gains (losses)			in Other													September 30,		3 Assets /
				included in			comprehensive													2012		Liabilities
				Income (1)			(income) loss															Outstanding at
																						September 30,
																						2012
Assets
Other assets:
Financial instruments owned:
Equity derivative contracts	$	1,937		$	(1,837	)	$	—		$	566		$	—	$	—	$	—		$	666	$	(1,837	)
Other:
Convertible note receivable, available-for-sale	$	5,362		$	(5,362	)	$	—		$	—		$	—	$	—	$	—		$	—	$	(5,362	)
Liabilities
Other liabilities:
Future purchase commitment	$	12,562		$	9,098		$	(180	)	$	—		$	—	$	—	$	—		$	3,644	$	9,098
Other liabilities:
Contingent consideration	$	1,119		$	(168	)	$	—		$	—		$	—	$	—	$	(478	)	$	809	$	(168	)
(1)                                     Realized and unrealized gains (losses) are reported in Other income in the Condensed Consolidated Statements of Operations, except  for the $5,362 impairment loss on the Convertible note receivable, available-for-sale, which was include within Other expenses in the Condensed Consolidated Statements of Operations
Quantitative Information about Level 3 Fair Value Measurements
The following tables present quantitative information about the significant unobservable inputs utilized by the Company in the fair value measurement of Level 3 Assets and Liabilities measured at fair value on a recurring basis, as of September 30, 2013 and December 31, 2012, respectively:
	Fair Value as of			Valuation		Unobservable Input(s)		Range (Weighted
	September 30,			Technique(s)				Average) (a)
	2013
Assets
Equity derivative contracts	$	14		Black-Scholes Merton Model		Expected volatility		35		%
						Estimated price per share		$	8.48
	Fair Value as of			Valuation		Unobservable Input(s)		Range (Weighted
	December 31,			Technique(s)				Average) (a)
	2012
Assets
Equity derivative contracts	$	28		Black-Scholes-Merton Model		Expected volatility		55		%
						Estimated price per share		$	4.07	(b)
Convertible note receivable, available-for-sale	$	—		Discounted cash flow		Estimated credit spread		19		%
				Black-Scholes-Merton Model		Expected volatility		45		%(c)
						Estimated price per convertible unit
Liabilities
Future purchase commitment	$	3,209		Present value of expected payments		Discount rate		15.5		%(d)
						Forecasted financial information
(a)         As of September 30, 2013 and December 31, 2012, each asset and liability type consists of one security.
(b)         Restated to reflect a 1-for-400 reverse split on the common stock of this investee, effective on April 23, 2013.
(c)          To determine the estimated price per convertible unit, the Company estimated the fair value of a non-controlling interest in the entity utilizing a discounted cash flow, appropriate discount rate and combined discount for lack of control and marketability.
(d)         The Company’s estimate of the Future Purchase Commitment as of December 31, 2012 was based on Kyte’s projected earnings through June 30, 2013. In estimating the fair value, the Company utilized post-tax projected earnings for the remaining period through June 30, 2013.
Valuation Processes—Level 3 Measurements—Depending on the instrument, the Company utilizes a valuation technique, including discounted cash flow methods, option pricing methods and present value methods, as indicated above.  Valuations are generally conducted by the Company, with consultation of a third-party valuation expert to develop the valuation model when the asset or liability is initially recorded. Each reporting period, the Company updates unobservable inputs utilizing relevant published information, where applicable. The Company has a formal process to review changes in fair value for satisfactory explanation.
Sensitivity Analysis—Level 3 Measurements
Equity derivative contracts - The significant unobservable inputs used in the fair value of the Company’s equity derivative contracts are the expected volatility and an estimated share price. Significant increases (decreases) in expected volatility or estimated share price would result in a higher (lower) fair value measurement.
Convertible note receivable, available-for-sale - The significant unobservable inputs used in the fair value of the Company’s convertible note receivable, available-for-sale, are an estimated credit spread, expected volatility and the estimated price per convertible unit. Significant increases (decreases) in expected volatility or estimated price per convertible unit would result in a higher (lower) fair value measurement. Significant increases (decreases) in the estimated credit spread would result in a lower (higher) fair value measurement.
Future purchase commitment — Prior to September 30, 2013, the Future Purchase Commitment relating to Kyte was settled and therefore, there is no sensitivity to the inputs used in determining its fair value.  As of December 31, 2012, the significant unobservable inputs used in the fair value of the Company’s Future Purchase Commitment for the residual 30% equity interest in Kyte were the discount rate and forecasted financial information. Significant increases (decreases) in the discount rate would have resulted in a lower (higher) fair value measurement. Significant increases (decreases) in the forecasted financial information would have resulted in a higher (lower) fair value measurement.
For all significant unobservable inputs used in the fair value measurement of all Level 3 assets and liabilities, a change in one of the inputs would not necessarily result in a directionally similar change in the other.

DERIVATIVE_FINANCIAL_INSTRUMEN

DERIVATIVE FINANCIAL INSTRUMENTS	9 Months Ended
	Sep. 30, 2013
DERIVATIVE FINANCIAL INSTRUMENTS	'
DERIVATIVE FINANCIAL INSTRUMENTS	'
	14.       DERIVATIVE FINANCIAL INSTRUMENTS
	The Company uses foreign exchange derivative contracts, including forward contracts and foreign currency swaps, to reduce the effects of fluctuations in certain assets and liabilities denominated in foreign currencies. The Company also hedges a portion of its foreign currency exposures on anticipated foreign currency denominated revenues and expenses by entering into forward foreign exchange contracts. As of September 30, 2013 and December 31, 2012, none of these contracts were designated as foreign currency cash flow hedges under ASC 815-10, Derivatives and Hedging (“ASC 815-10”).
	The Company provides brokerage services to its customers for exchange-traded and over-the-counter derivative products, which include futures, forwards and options contracts. The Company may enter into principal transactions for exchange-traded and over-the-counter derivative products to facilitate customer trading activities or to engage in principal trading for the Company’s own account.
	The Company monitors market risk exposure from its matched principal business and principal trading business by regularly monitoring its concentration of market risk to financial instruments, countries or counterparties and regularly monitoring trades that have not settled within prescribed settlement periods or volume thresholds. Additionally, market risks are monitored and mitigated by the use of the Company’s proprietary, electronic risk monitoring system, which provides daily credit reports in each of the Company’s geographic regions that analyze credit concentration and facilitates the regular monitoring of transactions against key risk indicators.
	For certain derivative contracts, the Company has entered into agreements with counterparties that allow for the netting of positions. The Company reports these derivative contracts on a net-by-counterparty basis when management believes that a legal and enforceable right of offset exists under these agreements.
	Fair values of derivative contracts on a gross and net basis as of September 30, 2013 and December 31, 2012 are as follows:
		September 30, 2013						December 31, 2012
	Derivatives not designated as hedging	Derivative			Derivative			Derivative			Derivative
	instruments under ASC 815-10	Assets (1)			Liabilities (2)			Assets (1)			Liabilities (2)
	Foreign exchange derivative contracts	$	20,843		$	21,646		$	182,388		$	182,628
	Commodity derivative contracts	37,755			37,756			23,656			23,680
	Fixed income derivative contracts	9,774			11,052			2,990			3,420
	Equity derivative contracts	23			9			42,811			34,460
	Total fair value of derivative contracts	$	68,395		$	70,463		$	251,845		$	244,188
	Counterparty netting	(68,112		)	(68,112		)	(227,968		)	(227,925		)
	Total fair value	$	283		$	2,351		$	23,877		$	16,263
	(1)                     Reflects futures and options on futures contracts within Receivables from brokers, dealers and clearing organizations and options and forwards contracts within Other assets.
	(2)                     Reflects futures and options on futures contracts within Payables to brokers, dealers and clearing organizations and options and forwards contracts within Other liabilities.
	As of September 30, 2013 and December 31, 2012, the Company had outstanding forward foreign exchange contracts with a combined notional value of $67,685 and $96,234, respectively. Approximately $27,105 and $26,390 of these forward foreign exchange contracts represents a hedge of euro-denominated and swiss franc-denominated balance sheet positions at September 30, 2013 and December 31, 2012, respectively. The remaining outstanding forward foreign exchange contracts are hedges of anticipated future cash flows.
	In addition to the Company’s outstanding forward foreign exchange contracts, the following table includes the outstanding long and short notional amounts on a gross basis of derivative financial instruments as of September 30, 2013 and December 31, 2012:
		September 30, 2013						December 31, 2012
		Long			Short			Long			Short
	Foreign exchange derivative contracts	$	848,045		$	729,818		$	13,131,184		$	13,116,622
	Commodity derivative contracts	768,443			770,117			592,686			592,923
	Fixed income derivative contracts	5,428,807			6,395,968			5,949,603			6,057,524
	Equity derivative contracts	5,861			367			81,841			430,899
	The following is a summary of the effect of derivative contracts on the Condensed Consolidated Statements of Operations for the three months ended September 30, 2013 and 2012:
		Location of Gain (Loss)		Amount of Gain (Loss) Recognized in Income on
				Derivatives
	Derivatives not designated as hedging	Recognized in Income		For the Three Months			For the Three Months
	instruments under ASC 815-10	on Derivatives		Ended September 30, 2013			Ended September 30, 2012
	Foreign exchange derivative contracts	-1		$	(500	)	$	1,463
	Commodity derivative contracts	Principal transactions		1,398			4,101
	Fixed income derivative contracts	Principal transactions		3,129			1,730
	Equity derivative contracts	-2		24			(1,424		)
	(1)         For the three months ended September 30, 2013, approximately $736 of losses on foreign exchange derivative contracts were included within Other income and approximately $236 of gains on foreign exchange derivative contracts were included within Principal transactions. For the three months ended September 30, 2012, approximately $460 of gains on foreign exchange derivative contracts were included within Other income and approximately $1,003 of gains on foreign currency options were included within Total brokerage revenues.
	(2)         For the three months ended September 30, 2013, approximately $24 of gains on equity derivative contracts were included within Principal transactions. For the three months ended September 30, 2012, approximately $1,709 of losses on equity derivative contracts were included within Other income and approximately $285 of gains on equity derivative contracts were included within Principal transactions.
	The following is a summary of the effect of derivative contracts on the Condensed Consolidated Statements of Income for the nine months ended September 30, 2013 and 2012:
		Location of Gain (Loss)		Amount of Gain (Loss) Recognized in Income on
				Derivatives
	Derivatives not designated as hedging	Recognized in Income		For the Nine Months			For the Nine Months Ended
	instruments under ASC 815-10	on Derivatives		Ended September 30, 2013			September 30, 2012
	Foreign exchange derivative contracts	-1		$	(1,926	)	$	6,334
	Commodity derivative contracts	Principal transactions		6,621			15,369
	Fixed income derivative contracts	Principal transactions		11,126			6,832
	Equity derivative contracts	-2		(164		)	(1,093		)
	(1)         For the nine months ended September 30, 2013, approximately $1,517 of losses on foreign exchange derivative contracts were included within Other income and approximately $409 of losses on foreign currency options were included within Principal transactions. For the nine months ended September 30, 2012, approximately $3,327 of gains on foreign exchange derivative contracts were included within Other income and approximately $3,007 of gains on foreign currency options were included within Principal transactions.
	(2)         For the nine months ended September 30, 2013, approximately $14 of losses on equity derivative contracts were included within Other income and approximately $150 of losses on equity derivative contracts were included within Principal transactions. For the nine months ended September 30, 2012, approximately $1,837 of losses on equity derivative contracts were included within Other income and approximately $744 of gains on equity derivative contracts were included within Principal transactions.
	The following is a summary of derivative contracts, by counterparty, including the gross amounts offset in the Condensed Consolidated Statements of Financial Position as of September 30, 2013:
		Gross			Gross Amounts			Net Amounts of			Gross Amounts Not Offset in the
					Offset in the			Assets Offset in the			Condensed Consolidated Statements
					Condensed			Condensed			of Financial Condition
	Counterparties	Amounts of			Consolidated			Consolidated			Derivatives (2)			Cash Collateral		Net Amount
		Recognized			Statements of			Statements of						Received/
		Assets			Financial Position			Financial Position (1)						(Pledged)
	Derivative Assets:
	Counterparty A	$	20,685		$	20,416		$	269		$	—		$	—	$	269
	Counterparty B	37,755			37,755			—			—			—		—
	Counterparty C	9,941			9,941			—			—			—		—
	Counterparty D	14			—			14			—			—		14
	Total	$	68,395		$	68,112		$	283		$	—		$	—	$	283
	Derivative Liabilities:
	Counterparty A	$	21,274		$	20,416		$	858		$	—		$	—	$	858
Counterparty B	37,756			37,755			1			—			—		1
Counterparty C	11,301			9,941			1,360			—			—		1,360
Counterparty E	132			—			132			—			—		132
Total	$	70,463		$	68,112		$	2,351		$	—		$	—	$	2,351
(1)         The total reconciles to the aggregate of total derivative contracts in the fair value measurements table and the variation margin on exchange traded futures for the respective periods; both reflected in Note 13. Derivative assets and derivative liabilities are reflected within Other assets and Other Liabilities, respectively, with the exception of futures and options on futures contracts. Futures and options on futures contracts are included within Receivables from and Payables to brokers, dealers, and clearing organizations, as applicable.
(2)         As of September 30, 2013, the Company does not have any derivative positions under a master netting agreement that are not netted.
The following is a summary of derivative contracts, by counterparty, including the gross amounts offset in the Condensed Consolidated Statements of Financial Position as of December 31, 2012:
	Gross			Gross Amounts			Net Amounts of			Gross Amounts Not Offset in the
				Offset in the			Assets Offset in the			Condensed Consolidated Statements
				Condensed			Condensed			of Financial Condition
							Consolidated
Counterparties	Amounts of			Consolidated			Statements of			Derivatives (2)			Cash Collateral		Net Amount
	Recognized			Statements of			Financial Position						Received/
	Assets			Financial Position			-1						(Pledged)
Derivative Assets:
Counterparty A	$	183,577		$	182,955		$	622		$	—		$	—	$	622
Counterparty B	16,987			16,938			49			—			—		49
Counterparty C	51,087			28,075			23,012			—			—		23,012
Counterparty D	28			—			28			—			—		28
Counterparty F	166			—			166			—			—		166
Total	$	251,845		$	227,968		$	23,877		$	—		$	—	$	23,877
Derivative Liabilities:
Counterparty A	$	183,973		$	182,912		$	1,061		$	—		$	—	$	1,061
Counterparty B	16,938			16,938			—			—			—		—
Counterparty C	43,277			28,075			15,202			—			—		15,202
Total	$	244,188		$	227,925		$	16,263		$	—		$	—	$	16,263
(1)         The total reconciles to the aggregate of total derivative contracts in the fair value measurements table and the variation margin on exchange traded futures for the respective periods; both reflected in Note 13. Derivative assets and derivative liabilities are reflected within Other assets and Other Liabilities, respectively, with the exception of futures and options on futures contracts. Futures and options on futures contracts are included within Receivables from and Payables to brokers, dealers, and clearing organizations, as applicable.
(2)         As of December 31, 2012, the Company does not have any derivative positions under a master netting agreement that are not netted.

VARIABLE_INTEREST_ENTITIES

VARIABLE INTEREST ENTITIES	9 Months Ended
	Sep. 30, 2013
VARIABLE INTEREST ENTITIES	'
VARIABLE INTEREST ENTITIES	'
	15.       VARIABLE INTEREST ENTITIES
	Non-consolidated VIEs
	The Company holds interests in certain VIEs that it does not consolidate. The Company has determined that it is not the primary beneficiary, mostly due to a lack of significant economic interest and/or power to direct the activities that would most significantly impact the economic performance of the VIE.
	As of September 30, 2013 and December 31, 2012, the Company had certain variable interests in non-consolidated VIEs in the form of direct equity interests and a convertible note. The carrying amount of these VIEs was $3,511 as of September 30, 2013 and $4,438 as of December 31, 2012, and was recorded within Other assets. These VIEs include a technology provider with a proprietary financial application, trading entities in which the Company has provided initial capital to fund trading activities, a commodity pool operator and an investment fund manager. The Company also provides clearing and other administrative services to certain of these non-consolidated VIEs. The maximum exposure to loss on these VIEs was $3,511 as of September 30, 2013 and $4,438 as of December 31, 2012.
	As of September 30, 2013 and December 31, 2012, the Company had certain variable interests in non-consolidated VIEs in the form of trading margin accounts in which the Company had an economic interest in profits and losses and provided initial capital to fund trading activities. The Company also provided clearing and other administrative services to these non-consolidated VIEs. The carrying amount of these VIEs was $1,596 as of September 30, 2013 and $9,784 as of December 31, 2012, and was recorded within Receivables from brokers, dealers and clearing organizations. The maximum exposure to loss of these VIEs was $1,596 as of September 30, 2013 and $10,703 as of December 31, 2012.
	The Company has not recorded any liabilities with respect to non-consolidated VIEs.
	Consolidated VIEs
	In December 2010, Kyte invested in a limited company that is focused on developing a proprietary trading business. The limited company is a VIE and it was determined that the Company is the primary beneficiary of this VIE because the Company, through Kyte, was the provider of the majority of this VIE’s start-up capital and has the power to direct the activities of this VIE that most significantly impact its economic performance, primarily through its voting percentage and consent rights on the activities that would most significantly influence the entity. The consolidated VIE had total assets of $9,550 and $6,428 at September 30, 2013, and December 31, 2012, respectively, which primarily consisted of clearing margin. There were no material restrictions on the consolidated VIE’s assets. The consolidated VIE had total liabilities of $3,433 at September 30, 2013 and $1,558 at December 31, 2012.

REGULATORY_REQUIREMENTS

REGULATORY REQUIREMENTS	9 Months Ended
	Sep. 30, 2013
REGULATORY REQUIREMENTS	'
REGULATORY REQUIREMENTS	'
	16.       REGULATORY REQUIREMENTS
	Many of the Company’s material operating subsidiaries are subject to regulatory restrictions and minimum capital requirements, which may restrict the Company’s ability to withdraw capital from its subsidiaries.
	Certain subsidiaries of the Company are registered as a U.S. broker-dealer, swap execution facility, introducing broker or Futures Commissions Merchant and therefore are subject to the applicable rules and regulations of the SEC and the Commodity Futures Trading Commission (“CFTC”). These rules contain uniform minimum net capital requirements, as defined, and also require a significant part of the registrants’ assets be kept in relatively liquid form.  As of September 30, 2013, each of the Company’s subsidiaries that are subject to these regulations had net capital in excess of their minimum capital requirements.
	Certain of the Company’s European subsidiaries are regulated by the Financial Conduct Authority (“FCA”) and must maintain financial resources (as defined by the FCA) in excess of FCA’s total financial resources requirement.  As of September 30, 2013, each of these European subsidiaries had financial resources in excess of their requirements.
	Certain other subsidiaries of the Company are subject to similar regulatory and other requirements in the jurisdictions in which they operate and as of September 30, 2013 each was in compliance with its regulatory capital requirements.
	The regulatory requirements referred to above may restrict the Company’s ability to withdraw capital from its regulated subsidiaries. As of September 30, 2013, the Company had the following aggregate regulatory capital, in individually regulated entities, in each of its operating regions:
		Americas		EMEA		Asia
	Regulatory capital	$	25,784	$	139,041	$	35,340
	Minimum regulatory capital required	7,395		112,957		8,194
	Excess regulatory capital	$	18,389	$	26,084	$	27,146
	The regulatory requirements set forth in the table above include aggregated amounts, in individually regulated entities, in each of the Company’s operating regions, calculated by entity, to comply with the requirements of various regulators for capital requirements in each of those entities.

SEGMENT_AND_GEOGRAPHIC_INFORMA

SEGMENT AND GEOGRAPHIC INFORMATION	9 Months Ended
	Sep. 30, 2013
SEGMENT AND GEOGRAPHIC INFORMATION	'
SEGMENT AND GEOGRAPHIC INFORMATION	'
	17.       SEGMENT AND GEOGRAPHIC INFORMATION
	In accordance with ASC 280-10, Segment Reporting (“ASC 280-10”) and based on the nature of the Company’s operations, products and services in each geographic region, the Company determined that it has five operating segments: (i) Americas Brokerage, (ii) Europe, Middle East and Africa (“EMEA”) Brokerage, (iii) Asia Brokerage, (iv) Clearing and Backed Trading and (v) All Other. The Company’s brokerage operations provide brokerage services in four broad product categories: fixed income, financial, equity and commodity. The Clearing and Backed Trading segment encompasses the Company’s clearing, risk management, settlement and other back-office services, as well as the capital we provide to start-up trading groups, small hedge funds, market-makers and individual traders. The All Other segment captures revenues and costs that are not directly assignable to one of the brokerage or clearing and backed trading operating segments, primarily consisting of the Company’s corporate business activities and operations from software, analytics and market data.
	The accounting policies of the segments are the same as those described above in Note 2—Summary of Significant Accounting Policies. The Company evaluates performance of the operating segments based on income (loss) before income taxes, which it defines as revenues less direct expenses. Revenues within each brokerage segment include revenues that are directly related to providing brokerage services along with interest and other income (loss) directly attributable to the operating segment. Revenues within the Clearing and Backed Trading segment primarily include revenues that are directly related to providing clearing services along with the Company’s share of profit (loss) on trading activity from capital investments. The Company’s Clearing and Backed Trading segment incurs exchanges fees on behalf of its clients, which are reflected within Interest and transaction-based expenses. The reimbursement of these fees from the Company’s clients is reflected within Total Revenues. Therefore, the Company evaluates the top-line performance of its Clearing and Backed Trading segment using Revenues, net of interest and transaction-based expenses. Direct expenses of the operating segments are those expenses that are directly related to providing the brokerage or clearing services and trading activities of the operating segments and include compensation expense related to the segment management and staff, communication and market data, travel and promotion, and certain professional fees and other expenses that are directly incurred by the operating segments. However, the Company does not allocate to its brokerage operating segments certain expenses that it manages separately at the corporate level. The unallocated costs include rent and occupancy, depreciation and amortization, professional fees, interest on borrowings and other expenses and are included in the All Other operating segment. Management generally does not consider the unallocated costs in its performance measurement of its reportable segments.
	Selected financial information for the Company’s reportable segments is presented below for periods indicated:
			Three Months Ended September 30, 2013
			Americas		EMEA		Asia		Clearing			All Other			Total
			Brokerage		Brokerage		Brokerage		and Backed
									Trading
	Total revenues		$	60,384	$	72,275	$	15,730	$	40,721		$	23,323		$	212,433
	Revenues, net of interest and transaction-based expenses		57,995		70,283		15,653		8,702			23,607			176,240
	Income (loss) before income taxes		15,515		19,078		3,438		(1,067		)	(38,120		)	(1,156		)
			Three Months Ended September 30, 2012
			Americas		EMEA		Asia		Clearing			All Other			Total
			Brokerage		Brokerage		Brokerage		and Backed
									Trading
	Total revenues		$	62,745	$	80,147	$	18,084	$	40,506		$	17,906		$	219,388
	Revenues, net of interest and transaction-based expenses		59,370		77,607		18,056		10,866			18,253			184,152
	Income (loss) before income taxes		14,392		19,889		4,722		515			(46,685		)	(7,167		)
			Nine Months Ended September 30, 2013
			Americas		EMEA		Asia		Clearing			All Other			Total
			Brokerage		Brokerage		Brokerage		and Backed
									Trading
	Total revenues		$	202,765	$	237,102	$	52,952	$	140,960		$	65,324		$	699,103
	Revenues, net of interest and transaction-based expenses		194,372		230,031		52,693		32,840			66,253			576,189
	Income (loss) before income taxes		56,139		65,756		13,257		2,492			(131,118		)	6,526
			Nine Months Ended September 30, 2012
			Americas		EMEA		Asia		Clearing			All Other			Total
			Brokerage		Brokerage		Brokerage		and Backed
									Trading
	Total revenues		$	216,674	$	263,564	$	58,010	$	121,744		$	57,301		$	717,293
	Revenues, net of interest and transaction-based expenses		205,825		255,751		57,948		35,642			58,447			613,613
	Income (loss) before income taxes		56,304		68,742		12,868		4,398			(134,143		)	8,169
	In addition, with the exception for goodwill, the Company does not identify or allocate assets by operating segment, nor does its chief operating decision maker evaluate operating segments using discrete asset information.  See Note 5 for goodwill by reportable segment.
	For the three and nine months ended September 30, 2013 and 2012, the U.K. is the only individual foreign country that accounts for 10% or more of the Company’s total revenues and total long-lived assets. Information regarding revenue for the three months ended September 30, 2013 and 2012, and information regarding long-lived assets (defined as property, equipment, leasehold improvements and software inventory) in geographic areas as of September 30, 2013 and December 31, 2012, are as follows:
			Three Months Ended				Nine Months Ended
			September 30,				September 30,
			2013		2012		2013		2012
	Revenues:
	United States		$	61,067	$	59,511	$	203,544	$	210,671
	United Kingdom		105,471		77,575		346,166		313,209
	Other		45,895		82,302		149,393		193,413
	Total		$	212,433	$	219,388	$	699,103	$	717,293
			Three Months Ended				Nine Months Ended
			September 30,				September 30,
			2013		2012		2013		2012
	Revenues, net of interest and transaction-based expenses:
	United States		$	60,010	$	57,556	$	199,181	$	204,183
	United Kingdom		72,764		46,780		235,884		223,506
	Other		43,467		79,816		141,124		185,924
	Total		$	176,240	$	184,152	$	576,189	$	613,613
					September 30,		December 31,
					2013		2012
		Long-lived Assets, as defined:
		United States			$	49,777	$	47,675
		United Kingdom			11,510		10,536
		Other			4,767		5,239
		Total			$	66,054	$	63,450
	Revenues are attributed to geographic areas based on the location of the particular subsidiary of the Company which generated the revenues.

SUBSEQUENT_EVENTS

SUBSEQUENT EVENTS	9 Months Ended
	Sep. 30, 2013
SUBSEQUENT EVENTS	'
SUBSEQUENT EVENTS	'
	18.       SUBSEQUENT EVENTS
	In October 2013, the Board of Directors declared a quarterly cash dividend of $0.05 per share payable on November 29, 2013 to stockholders of record on November 15, 2013.
	Subsequent events have been evaluated for recording and disclosure in the notes to the Condensed Consolidated Financial Statements through the filing date of this Form 10-Q.

SUMMARY_OF_SIGNIFICANT_ACCOUNT1

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
	Sep. 30, 2013
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	'
Basis of Presentation	'
	Basis of Presentation—The Company’s Condensed Consolidated Financial Statements (Unaudited) are prepared in accordance with accounting principles generally accepted in the United States of America, which require management to make estimates and assumptions that affect the reported amounts of assets and liabilities, revenues and expenses, and the disclosure of contingencies in the Condensed Consolidated Financial Statements. Certain estimates and assumptions relate to the accounting for acquired goodwill and intangible assets, fair value measurements, compensation accruals, tax assets and liabilities, and the potential outcome of litigation matters. Management believes that the estimates utilized in the preparation of the Condensed Consolidated Financial Statements are reasonable and prudent. Actual results could differ materially from these estimates.
	Certain amounts in the Condensed Consolidated Statements of Cash Flows have been reclassified to conform to the current year presentation.
	These Condensed Consolidated Financial Statements are unaudited and should be read in conjunction with the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2012. References to the Company’s “2012 Form 10-K” are to the Company’s Annual Report on Form 10-K for the year ended December 31, 2012. The condensed consolidated financial information as of December 31, 2012 presented in this Form 10-Q has been derived from audited Consolidated Financial Statements not included herein.
	These unaudited Condensed Consolidated Financial Statements reflect all adjustments that are, in the opinion of management, necessary for a fair statement of the results for the interim periods presented. These adjustments are of a normal, recurring nature. Interim period operating results may not be indicative of the operating results for a full year.
Consolidation Policies	'
	Consolidation Policies
	General—The Condensed Consolidated Financial Statements include the accounts of the Company, its wholly-owned subsidiaries and subsidiaries that are treated as such and other entities in which the Company has a controlling financial interest. For consolidated subsidiaries that are less than wholly-owned, equity interests that are not owned by the Company are referred to as non-controlling interests. The portion of net income attributable to non-controlling interests for such subsidiaries is presented as Net income attributable to non-controlling interests on the Condensed Consolidated Statements of Operations, and the portion of the stockholders’ equity of such subsidiaries is presented as Non-controlling interests in the Condensed Consolidated Statements of Financial Condition and Condensed Consolidated Statement of Changes in Stockholders’ Equity. All intercompany transactions and balances have been eliminated.
Variable Interest Entities	'
	Variable Interest Entities—The Company determines whether it holds any interests in entities deemed to be a variable interest entity (“VIE”). A VIE is an entity that lacks one or more of the following characteristics (i) the total equity investment at risk is sufficient to enable the entity to finance its activities independently and (ii) the equity holders have the power to direct the activities of the entity that most significantly impact its economic performance, the obligation to absorb the losses of the entity and the right to receive the residual returns of the entity. The Company has a controlling financial interest and will consolidate a VIE if it is the primary beneficiary.
	The primary beneficiary is the party that has both (i) the power to direct the activities of the VIE that most significantly impact the economic performance of the entity and (ii) the obligation to absorb losses of the entity that could be potentially significant to the VIE or the right to receive benefits from the entity that could be potentially significant.
	As of September 30, 2013, the company holds interests in certain VIEs. One of these VIEs is consolidated because it was determined that the Company is the primary beneficiary of this VIE because (1) the Company provided the majority of the VIE’s start-up capital and (2) the Company has consent rights regarding those activities that the Company believes would most significantly impact the economic performance of the entity. The remaining VIEs are not consolidated as it was determined that the Company is not the primary beneficiary based on the level of equity ownership and voting power. The Company reassesses its evaluation of whether an entity is a VIE when certain events occur, such as changes in economic ownership and voting power. The Company reassesses its determination of whether it is the primary beneficiary of a VIE on an ongoing basis based on current facts and circumstances.  See Note 15 for disclosures on Variable Interest Entities.
Cash and Cash Equivalents	'
	Cash and Cash Equivalents—Cash and cash equivalents consist of cash and highly liquid investments with maturities, when purchased, of three months or less.
Cash and Securities Segregated Under Federal and Other Regulations	'
	Cash and Securities Segregated Under Federal and Other Regulations—The Company holds cash and securities representing funds received in connection with customer trading activities. The Company’s subsidiaries are required to satisfy regulations mandated by their primary regulators to segregate or set aside cash or equivalent securities to satisfy regulations, promulgated to protect customer assets.
Commissions Receivable	'
	Commissions Receivable—Commissions receivable represents amounts due from brokers, dealers, banks and other financial and nonfinancial institutions for the execution of securities, commodities, foreign exchange and other derivative brokerage transactions. In estimating the allowance for doubtful accounts, management considers the length of time receivables are past due and historical experience. In addition, if the Company is aware of a client’s inability to meet its financial obligations, a specific provision for doubtful accounts is recorded in the amount of the estimated losses that will result from the inability of that client to meet its financial obligation.
Receivables from and Payables to Brokers, Dealers and Clearing Organizations	'
	Receivables from and Payables to Brokers, Dealers and Clearing Organizations—Receivables from and payables to brokers, dealers and clearing organizations primarily represent: (i) principal transactions for which the stated settlement dates have not yet been reached, (ii) principal transactions which have not settled as of their stated settlement dates, (iii) cash, including deposits, held at clearing organizations and exchanges in support of the Company’s clearing business and to facilitate settlement and clearance of matched principal transactions and (iv) the spread on matched principal transactions that have not yet been remitted from/to clearing organizations and exchanges.
Property, Equipment and Leasehold Improvements	'
	Property, Equipment and Leasehold Improvements—Property, equipment and leasehold improvements are stated at cost, less accumulated depreciation and amortization. Depreciation and amortization are calculated using the straight-line method, generally over three to seven years. Property and equipment are depreciated over their estimated useful lives. Leasehold improvements are amortized over the shorter of the remaining term of the respective lease to which they relate or the remaining useful life of the leasehold improvement. Internal and external costs incurred in developing or obtaining computer software for internal use are capitalized in accordance with Accounting Standards Codification (“ASC”) 350 Intangibles—Goodwill and Other (“ASC 350”), and are amortized on a straight-line basis over the estimated useful life of the software, generally three years. General and administrative costs related to developing or obtaining such software are expensed as incurred.
Goodwill and Intangible Assets	'
	Goodwill and Intangible Assets—Goodwill represents the excess of the purchase price allocation over the fair value of tangible and identifiable intangible net assets acquired. The goodwill associated with each business combination is allocated to the related reporting units, which are determined based on how the Company’s businesses are managed and how they are reviewed by the Company’s chief operating decision maker. Other intangible assets are recorded at their fair value upon completion of a business combination or certain other transactions.
	In accordance with ASC 350, goodwill and other intangible assets with indefinite lives are not amortized, but instead are periodically tested for impairment. The Company reviews goodwill and other intangible assets with indefinite lives for impairment on an annual basis as of November 1 of each fiscal year or whenever an event occurs or circumstances change that could reduce the fair value of a reporting unit below its carrying amount.
	Intangible assets with definite lives are amortized on a straight-line basis over their estimated useful lives. See Note 5 for further information.
Prepaid Bonuses and Forgivable Employee Loans	'
	Prepaid Bonuses and Forgivable Employee Loans—Prepaid bonuses and forgivable loans to employees are stated at historical value net of amortization when the agreement between the Company and the employee provides for the return of proportionate amounts of the bonus or loan outstanding if employment is terminated in certain circumstances prior to the end of the term of the agreement. Amortization is calculated using the straight-line method over the term of the contract, which is generally two to four years, and is recorded in Compensation and employee benefits. The Company generally expects to recover the unamortized portion of prepaid bonuses and forgivable loans when employees voluntarily terminate their employment or if their employment is terminated for cause prior to the end of the term of the agreement. The prepaid bonuses and forgivable loans are included in Other assets in the Condensed Consolidated Statements of Financial Condition. At September 30, 2013 and December 31, 2012, the Company had prepaid bonuses of $25,833 and $31,847, respectively. At September 30, 2013 and December 31, 2012, the Company had forgivable employee loans and advances to employees of $26,009 and $31,655, respectively. Amortization of prepaid bonuses and forgivable employee loans for the nine months ended September 30, 2013 and 2012 was $19,904 and $19,727, respectively and is included within Compensation and employee benefits.
Investments	'
	Investments— When the Company does not have a controlling financial interest in an entity but can exert significant influence over the entity’s operating and financial policies, the investment is accounted for under the equity method of accounting in accordance with ASC 323-10, Investments—Equity Method and Joint Ventures (“ASC 323-10”). Significant influence generally exists when the Company owns 20% to 50% of the entity’s common stock or in-substance common stock. The Company initially records the investment at cost and adjusts the carrying amount each period to recognize its share of the earnings or losses of the investee based on the percentage of ownership. At September 30, 2013 and December 31, 2012, the Company had equity method investments with a carrying value of $37,057 and $26,743, respectively, included within Other assets. The Company also provides clearing and other administrative services to certain of these equity method investees.
	Investments for which the Company does not have the ability to exert significant influence over operating and financial policies are generally accounted for using the cost method of accounting in accordance with ASC 325-10, Investments—Other (“ASC 325-10”). At September 30, 2013 and December 31, 2012, the Company had cost method investments of $5,064 and $4,671, respectively, included within Other assets. The fair value of the Company’s cost method investments are not estimated if there are no identified events or changes in circumstances that may have a significant adverse effect on the fair value. The Company monitors its equity and cost method investments for indicators of impairment each reporting period.
	The Company accounts for its marketable equity securities and its debt securities in accordance with ASC 320-10, Investments—Debt and Equity Securities. Investments that are owned by the Company’s broker-dealer subsidiaries are recorded at fair value with realized and unrealized gains and losses reported in net income. Investments designated as available-for-sale that are owned by the Company’s non broker-dealer subsidiaries are recorded at fair value with unrealized gains or losses reported as a separate component of other comprehensive income, net of tax. The fair value of the Company’s available-for-sale securities was $4,354 and $3,355 as of September 30, 2013 and December 31, 2012, respectively, and is included within Other assets.
Fair Value of Financial Instruments	'
	Fair Value of Financial Instruments—In accordance with ASC 820-10, Fair Value Measurements and Disclosures (“ASC 820-10”), the Company estimates fair values of financial instruments using relevant market information and other assumptions. Fair value estimates involve uncertainties and matters of significant judgment in interpreting market data and, accordingly, changes in assumptions or in market conditions could adversely affect the estimates. The Company also discloses the fair value of its financial instruments in accordance with the fair value hierarchy as set forth by ASC 820-10. See Note 13 for further information.
Fair Value Option	'
	Fair Value Option—In accordance with ASC 825-10-25, Financial Instruments - Recognition, upon the acquisition of The Kyte Group Limited and Kyte Capital Management Limited (collectively “Kyte”), the Company elected the fair value option to account for its then future commitment to purchase the remaining 30% equity interest in Kyte.  See Note 4 for further discussion regarding this future purchase commitment.
	The fair value option election allows companies to irrevocably elect fair value as the initial and subsequent measurement attribute for certain financial assets and liabilities. Any change in fair value for assets and liabilities for which the election is made is to be recognized in earnings as they occur. The fair value option election is permitted on an instrument by instrument basis at initial recognition of an asset or liability or upon an event that gives rise to a new basis of accounting for that instrument.
	The primary reason for electing the fair value option on the then future commitment to purchase the remaining 30% equity interest in Kyte was to timely reflect economic events in earnings, as management’s assessment of the future purchase commitment value was driven by Kyte’s earnings or losses subsequent to the initial acquisition date and net present value at a specific point in time.
Derivative Financial Instruments	'
	Derivative Financial Instruments—The Company enters into derivative transactions for a variety of reasons, including managing its exposure to risk arising from changes in foreign currency, facilitating customer trading activities and, in certain instances, to engage in principal trading for the Company’s own account. Derivative assets and liabilities are carried on the Condensed Consolidated Statements of Financial Condition at fair value, with changes in the fair value recognized in the Condensed Consolidated Statements of Operations. Contracts entered into to manage risk arising from changes in foreign currency are recognized in Other income and contracts entered into to facilitate customer transactions and principal trading are recognized in Principal transactions. Derivatives are reported on a net-by-counterparty basis when management believes that a legal and enforceable right of offset exists under these agreements. See Note 14 for further information.
Payables to Clearing Services Customers	'
	Payables to Clearing Services Customers—Payables to clearing services customers include amounts due on cash and margin transactions, including futures contracts, executed on behalf of customers.
Brokerage Transactions	'
	Brokerage Transactions—The Company provides brokerage services to its clients in the form of either agency or principal transactions.
	Agency Commissions—In agency transactions, the Company charges commissions for executing transactions between buyers and sellers. Agency commission revenues and related expenses are recognized on a trade date basis.
	Principal Transactions—Principal transactions revenue is primarily derived from matched principal and principal trading transactions. Principal transactions revenues and related expenses are recognized on a trade date basis. The Company earns revenue from principal transactions on the spread between the buy and sell price of the security that is brokered. In matched principal transactions, the Company simultaneously agrees to buy instruments from one customer and sell them to another customer.
	In the normal course of its matched principal and principal trading businesses, the Company may hold security positions overnight. These positions are marked to market on a daily basis.
Clearing Services Revenues	'
	Clearing Services Revenues—The Company charges fees to customers for clearing services provided for cash and derivative transactions. Clearing services revenues are recorded on a trade date basis as customer transactions occur and are presented net of any customer negotiated rebates.
Software, Analytics and Market Data Revenue Recognition	'
	Software, Analytics and Market Data Revenue Recognition—Software revenue consists primarily of fees charged for Trayport electronic trading software, which are typically billed on a subscription basis and are recognized ratably over the term of the subscription period, which ranges from one to five years. Analytics revenue consists primarily of software license fees for Fenics® pricing tools which are typically billed on a subscription basis, and is recognized ratably over the term of the subscription period, which is generally three years. Market data revenue primarily consists of subscription fees and fees from customized one-time sales. Market data subscription fees are recognized on a straight-line basis over the term of the subscription period, which ranges from one to two years. Market data revenue from customized one-time sales is recognized upon delivery of the data.
	The Company markets its software, analytics and market data products through its direct sales force and, in some cases, indirectly through resellers. In general, the Company’s license agreements for such products do not provide for a right of return.
Other Income	'
	Other Income—Included within Other income on the Company’s Condensed Consolidated Statements of Operations are revaluations of foreign currency derivative contracts, realized and unrealized transaction gains and losses on certain foreign currency denominated items, and gains and losses on certain investments, and interest income earned on short-term investments.
Compensation and Employee Benefits	'
	Compensation and Employee Benefits—The Company’s compensation and employee benefits have both a fixed and variable component. Base salaries and benefit costs are primarily fixed for all employees while bonuses constitute the variable portion of compensation and employee benefits. The Company may pay certain performance bonuses in restricted stock units (“RSUs”). The Company also may grant sign-on and retention bonuses for certain newly-hired or existing employees who agree to long-term employment agreements.
Share-Based Compensation	'
	Share-Based Compensation—The Company’s share-based compensation consists of RSUs. The Company accounts for share-based compensation in accordance with ASC 718 Compensation— Stock Compensation (“ASC 718”). This accounting guidance requires measurement of compensation expense for equity-based awards at fair value and recognition of compensation expense over the service period, net of estimated forfeitures. In all periods presented, the only share-based compensation expense recognized by the Company has been RSUs. The Company determines the fair value of RSUs based on the number of units granted and the grant date fair value of the Company’s common stock, measured as of the closing price on the date of grant. See Note 10 for further information.
Income Taxes	'
	Income Taxes— In accordance with ASC 740, Income Taxes (“ASC 740”), the Company provides for income taxes using the asset and liability method under which deferred income taxes are recognized for the estimated future tax effects attributable to temporary differences and carryforwards that result from events that have been recognized either in the financial statements or the income tax returns, but not both. The measurement of current and deferred income tax assets and liabilities is based on provisions of enacted tax laws. Valuation allowances are recognized if, based on the weight of available evidence, it is more likely than not that some portion of the deferred tax assets will not be realized. Management applies the more likely than not criteria prior to recognizing a financial statement benefit for a tax position taken (or expected to be taken) in a tax return. The Company recognizes interest and/or penalties related to income tax matters in interest expense and other expense, respectively.
	The Company normally determines its interim provision for or benefit from income taxes using an estimated annual effective tax rate methodology as required by ASC 740.  However, the Company has utilized a discrete period method to calculate taxes for the three and nine months ended September 30, 2013 based on actual results. The Company has determined that the calculation of an annual effective tax rate would not represent a reliable estimate due to the sensitivity of this estimated rate to minimal changes in the forecasted pre-tax income (loss) for the fourth quarter of 2013. Under the discrete method, the Company determines its provision for or benefit from income taxes based on the actual results for the nine months ended September 30, 2013 as if this interim period were an annual period.
	The decrease in the Company’s effective tax rate for the nine months ended September 30, 2013 as compared to the nine months ended September 30, 2012 was primarily due to: (i) changes in the geographic mix of profits, (ii) a tax benefit under the American Taxpayer Relief Act of 2012 related to taxes previously provided for, (iii) a tax benefit arising from a change in the Company’s view about the deductibility of a reserve previously deemed nondeductible, as a result of new information received in the first quarter of 2013, and (iv) the release of a tax liability in a foreign subsidiary where the statute of limitations has now expired.
Treasury Stock	'
	Treasury Stock—The Company accounts for Treasury stock using the cost method. Treasury stock held by the Company may be reissued with respect to vested RSUs in qualified jurisdictions. The Company’s policy is to account for these shares as a reduction of Treasury stock on a first-in, first-out basis.
Foreign Currency Translation Adjustments and Transactions	'
	Foreign Currency Translation Adjustments and Transactions— Assets and liabilities of foreign subsidiaries having non-U.S. dollar functional currencies are translated at the period end rates of exchange, and revenue and expenses are translated at the average rates of exchange for the period. Gains or losses resulting from translating the foreign currency financial statements are reflected in foreign currency translation adjustments and are reported as a separate component of comprehensive income (loss) and included in accumulated other comprehensive income in the Condensed Consolidated Statement of Changes in Stockholders’ Equity. The revaluation of asset and liability balances that are denominated in currencies other than the functional currency of the business unit involved in such transactions is reflected in Other Income in the Condensed Consolidated Statements of Operations. Net gains (losses) resulting from remeasurement of foreign currency transactions and balances were $2,212 and $(1,113) for the three months ended September 30, 2013 and 2012, respectively, and $1,757 and $(3,835) for the nine months ended September 30, 2013 and 2012, respectively.
	During the three and nine months ended September 30, 2013, the Company reclassified a $1,645 foreign currency translation gain out of Accumulated other comprehensive income and into the Condensed Consolidated Statement of Operations. The amount was included within Other income and was reclassified during the current period due to the substantial liquidation of a foreign subsidiary, to which this gain was related.  The reclassification had no effect on the benefit from income taxes on the Condensed Consolidated Statement of Operations.
Recent Accounting Pronouncements	'
	Recent Accounting Pronouncements—In December 2011, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2011-11, Balance Sheet (Topic 210): Disclosures about Offsetting Assets and Liabilities (“ASU 2011-11”). ASU 2011-11 requires additional disclosure about financial instruments and derivatives instruments that are subject to netting arrangements to assist users of the financial statements in understanding the effect of those arrangements on its financial position.  In January 2013, the FASB issued an amendment to ASU 2011-11, ASU No. 2013-01 Balance Sheet (Topic 210): Clarifying the Scope of Disclosure about Offsetting Assets and Liabilities (“ASU 2013-01”).  ASU 2013-01 clarifies that the scope of ASU 2011-11 applies to derivatives accounted for in accordance with ASC 815- Derivatives and Hedging, including bifurcated embedded derivatives, repurchase agreements and reverse repurchase agreements, and securities borrowing and securities lending transaction that are either offset in accordance with Balance Sheet (Topic 210) guidance, Derivatives and Hedging (Topic 815) guidance, or subject to an enforceable master netting arrangement or similar agreement. The new disclosures were required for reporting periods beginning on or after January 1, 2013, including retrospectively for all comparative periods presented.  The adoption of ASU 2013-01 did not have a material impact on the Company’s Condensed Consolidated Financial Statements. See Note 14 for disclosures.
	In February 2013, the FASB issued ASU No. 2013-02, Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income (“ASU 2013-02”), regarding the reporting of reclassifications out of accumulated other comprehensive income. The new guidance does not change current requirements for reporting net income or other comprehensive income in financial statements. However, it requires companies to present the effects on the line items of net income of significant amounts reclassified out of accumulated other comprehensive income if the item reclassified is required to be reclassified to net income in its entirety during the same reporting period. Presentation should occur either on the face of the income statement where net income is presented or in the notes to the financial statements.  See Accounting Policy on Foreign Currency Translation Adjustments and Transactions for impact on the Condensed Consolidated Financial Statements during the three and nine months ended September 30, 2013.
	In July 2013, the FASB issued ASU No. 2013-11, Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists (“ASU 2013-11”). ASU 2013-11 requires an entity to present an unrecognized tax benefit, or a portion of an unrecognized tax benefit, in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss or tax credit carryforward, unless such tax loss or credit carryforward is not available at the reporting date under the tax law of the applicable jurisdiction to settle any additional income taxes resulting from the disallowance of a tax position. In the event that the tax position is disallowed or the tax law of the applicable jurisdiction does not require the entity to use, and the entity does not intend to use, the deferred tax asset for such purpose, the unrecognized tax benefit shall be presented in the financial statements as a liability and shall not be combined with deferred tax assets. The guidance is effective for annual reporting periods beginning after December 15, 2013, and interim periods within those annual periods, and is to be applied prospectively. The Company is currently evaluating the impact of its pending adoption of ASU 2013-11 on its Condensed Consolidated Financial Statements.

RECEIVABLES_FROM_AND_PAYABLES_1

RECEIVABLES FROM AND PAYABLES TO BROKERS, DEALERS AND CLEARING ORGANIZATIONS (Tables)	9 Months Ended
	Sep. 30, 2013
RECEIVABLES FROM AND PAYABLES TO BROKERS, DEALERS AND CLEARING ORGANIZATIONS	'
Schedule of amounts receivable from and payable to brokers, dealers and clearing organizations	'
		September 30,		December 31,
		2013		2012
	Receivables from brokers, dealers and clearing organizations:
	Contract value of fails to deliver	$	520,516	$	164,090
	Receivables from and deposits with clearing organizations and financial institutions	123,048		87,348
	Net pending trades	3,465		1,258
	Total	$	647,029	$	252,696
	Payables to brokers, dealers and clearing organizations:
	Contract value of fails to receive	$	486,445	$	158,256
	Payables to clearing organizations and financial institutions	26,615		6,679
	Total	$	513,060	$	164,935
Cash and securities segregated under federal and other regulations or Receivables from brokers, dealers and clearing organizations	'
		September 30,		December 31,
		2013		2012
	Cash and cash equivalents	$	—	$	27,623
	Cash segregated under federal and other regulations	60,598		47,300
	Receivables from brokers, dealers, and clearing organizations	75,617		64,704
	Total	$	136,215	$	139,627

GOODWILL_AND_INTANGIBLE_ASSETS1

GOODWILL AND INTANGIBLE ASSETS (Tables)	9 Months Ended
	Sep. 30, 2013
GOODWILL AND INTANGIBLE ASSETS	'
Schedule of changes in the carrying amount of the Company's goodwill	'
		December 31,		Goodwill		Foreign currency			September 30,
		2012		Acquired		translation			2013
	Goodwill
	Americas Brokerage	$	83,289	$	—	$	—		$	83,289
	EMEA Brokerage	14,397		—		(48		)	14,349
	Asia Brokerage	—		—		—			—
	Clearing and Backed Trading	41,600		—		(158		)	41,442
	All Other	128,691		—		—			128,691
		$	267,977	$	—	$	(206	)	$	267,771
Schedule of intangible assets	'
		September 30, 2013							December 31, 2012
		Gross		Accumulated		Net			Gross		Accumulated		Net
		amount		amortization		carrying			amount		amortization		carrying
				and foreign		value					and foreign		value
				currency							currency
				translation							translation
	Intangible assets
	Customer relationships	$	78,896	$	41,492	$	37,404		$	77,426	$	35,597	$	41,829
	Trade names	8,951		6,565		2,386			8,951		6,181		2,770
	Core technology	6,400		6,400		—			6,400		5,835		565
	Non-compete agreements	4,204		3,806		398			3,874		3,656		218
	Favorable lease agreements	620		560		60			620		500		120
	Patents	3,131		1,097		2,034			3,131		723		2,408
	Other	647		257		390			647		65		582
	Total	$	102,849	$	60,177	$	42,672		$	101,049	$	52,557	$	48,492
Schedule of expected amortization expense for intangible assets	'
	2013 (remaining three months)	$	2,267
	2014	9,015
	2015	8,909
	2016	6,878
	2017	3,494
	Thereafter	12,109
	Total	$	42,672

OTHER_ASSETS_AND_OTHER_LIABILI1

OTHER ASSETS AND OTHER LIABILITIES (Tables)	9 Months Ended
	Sep. 30, 2013
OTHER ASSETS AND OTHER LIABILITIES	'
Schedule of other assets	'
		September 30,		December 31,
		2013		2012
	Deferred tax assets	$	51,046	$	41,567
	Investments accounted for under the cost method and equity method	42,121		31,414
	Forgivable employee loans and advances to employees	26,009		31,655
	Prepaid bonuses	25,833		31,847
	Deferred financing fees	6,942		8,074
	Financial instruments owned	2,981		25,250
	Software inventory, net	2,905		4,615
	Other	28,726		28,774
	Total Other assets	$	186,563	$	203,196
Schedule of other liabilities	'
		September 30,		December 31,
		2013		2012
	Payroll related liabilities	$	27,685	$	15,418
	Deferred revenues	9,251		7,247
	Unrecognized tax benefits	8,956		8,957
	Deferred tax liabilities	6,715		7,943
	Financial instruments sold, not yet purchased	1,567		1,481
	Future purchase commitment and contingent consideration liabilities	100		3,727
	Other	31,237		38,801
	Total Other liabilities	$	85,511	$	83,574

SHORTTERM_BORROWINGS_AND_LONGT1

SHORT-TERM BORROWINGS AND LONG-TERM OBLIGATIONS (Tables)	9 Months Ended
	Sep. 30, 2013
SHORT-TERM BORROWINGS AND LONG-TERM OBLIGATIONS	'
Schedule of the Company's outstanding debt obligations	'
		September 30,		December 31,
		2013		2012
	8.375% Senior Notes due 2018	$	240,000	$	250,000
	Loans pursuant to Credit Agreement	10,000		—
	Total	$	250,000	$	250,000
Schedule of the carrying amounts and estimated fair values of the Company's Long-term obligations	'
		September 30, 2013				December 31, 2012
		Carrying		Fair Value		Carrying		Fair Value
		Amount				Amount
	8.375% Senior Notes	$	240,000	$	242,700	$	250,000	$	220,720

LOSS_EARNINGS_PER_SHARE_Tables

(LOSS) EARNINGS PER SHARE (Tables)	9 Months Ended
	Sep. 30, 2013
(LOSS) EARNINGS PER SHARE	'
Schedule of basic and diluted (loss) earnings per share	'
		Three Months Ended September 30,						Nine Months Ended September 30,
		2013			2012			2013		2012
	Basic (loss) earnings per share
	GFI’s net (loss) income	$	(461	)	$	(8,693	)	$	10,904	$	1,419
	Weighted average common shares outstanding	120,331,179			115,541,373			118,138,756		116,073,488
	Basic (loss) earnings per share	$	(0.00	)	$	(0.08	)	$	0.09	$	0.01
	Diluted (loss) earnings per share
	GFI’s net (loss) income	$	(461	)	$	(8,693	)	$	10,904	$	1,419
	Weighted average common shares outstanding	120,331,179			115,541,373			118,138,756		116,073,488
	Effect of dilutive options, RSUs, and other contingently issuable shares	—			—			8,719,703		7,496,622
	Weighted average shares outstanding and common stock equivalents	120,331,179			115,541,373			126,858,459		123,570,110
	Diluted (loss) earnings per share	$	(0.00	)	$	(0.08	)	$	0.09	$	0.01

SHAREBASED_COMPENSATION_Tables

SHARE-BASED COMPENSATION (Tables)	9 Months Ended
	Sep. 30, 2013
SHARE-BASED COMPENSATION	'
Summary of RSU activity	'
		RSUs		Weighted-
				Average
				Grant Date
				Fair Value
	Outstanding December 31, 2012	19,353,382		$	4.27
	Granted	6,554,167		3.71
	Vested	(6,338,258	)	4.48
	Cancelled	(885,739	)	4.01
	Outstanding September 30, 2013	18,683,552		$	4.02
Schedule of total compensation expense and related income tax benefits recognized in relation to RSUs	'
		Three Months Ended September 30,						Nine Months Ended September 30,
		2013			2012			2013			2012
	Compensation expense	$	6,870		$	7,751		$	22,372		$	24,653
	Income tax benefits	$	1,913		$	2,359		$	6,655		$	7,506
Stock options outstanding under both the GFI Group 2002 Plan and the GFInet 2000 Plan	'
		GFI Group 2002 Plan					GFInet 2000 Plan
		Options		Weighted			Options		Weighted
				Average					Average
				Exercise					Exercise
				Price					Price
	Outstanding December 31, 2012	575,220		$	3.29		16,844		$	2.97
	Exercised	(205,952	)	2.97			(16,844	)	2.97
	Cancelled	(10,104	)	2.97			—		—
	Expired	(3,156	)	4.78			—		—
	Outstanding September 30, 2013	356,008		$	3.42		—		$	—

FAIR_VALUE_OF_FINANCIAL_INSTRU1

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	9 Months Ended
	Sep. 30, 2013
FAIR VALUE OF FINANCIAL INSTRUMENTS	'
Schedule of financial assets and liabilities measured at fair value on a recurring basis	'
	Financial Assets and Liabilities measured at fair value on a recurring basis as of September 30, 2013 are as follows:
		Quoted Prices in			Significant Other			Significant			Balance at
		Active Markets for			Observable			Unobservable			September 30,
		Identical Assets			Inputs			Inputs			2013
		(Level 1)			(Level 2)			(Level 3)
	Assets
	Other assets: Financial instruments owned:
	Equity securities	$	2,521		$	177		$	—		$	2,698
	Derivative contracts:
	Foreign exchange derivative contracts	$	4		$	20,685		$	—		$	20,689
	Fixed income derivative contracts	1,208			—			—			1,208
	Equity derivative contracts	—			—			14			14
	Commodity derivative contracts	—			—			—			—
	Netting (1)	(1,212		)	(20,416		)	—			(21,628		)
	Total derivative contracts	$	—		$	269		$	14		$	283
	Total financial instruments owned	$	2,521		$	446		$	14		$	2,981
	Other assets: Other:
	Equity security, available-for-sale	$	4,354		$	—		$	—		$	4,354
	Total	$	6,875		$	446		$	14		$	7,335
	Liabilities
	Other liabilities: Financial instruments sold, not yet purchased:
	Equity securities	$	24		$	—		$	—		$	24
	Foreign government bonds	68			—			—			68
	Derivative contracts:
	Foreign exchange derivative contracts	$	91		$	21,406		$	—		$	21,497
	Fixed income derivative contracts	1,606			—			—			1,606
	Equity derivative contracts	—			—			—			—
	Commodity derivative contracts	—			—			—			—
	Netting (1)	(1,212		)	(20,416		)	—			(21,628		)
	Total derivative contracts	$	485		$	990		$	—		$	1,475
	Total financial instruments sold, not yet purchased	$	577		$	990		$	—		$	1,567
	Other liabilities: Future purchase commitment	$	—		$	—		$	—		$	—
	Other liabilities: Contingent consideration	$	—		$	—		$	100		$	100
	Total	$	577		$	990		$	100		$	1,667
	(1)         Represents the impact of netting on a net-by-counterparty basis.
	Financial Assets and Liabilities measured at fair value on a recurring basis as of December 31, 2012 are as follows:
		Quoted Prices in			Significant Other			Significant			Balance at
		Active Markets for			Observable			Unobservable			December 31,
		Identical Assets			Inputs			Inputs			2012
		(Level 1)			(Level 2)			(Level 3)
	Assets
	Other assets: Financial instruments owned:
	Equity securities	$	1,223		$	199		$	—		$	1,422
	Derivative contracts:
	Foreign exchange derivative contracts	$	—		$	182,343		$	—		$	182,343
	Fixed income derivative contracts	394			—			—			394
	Equity derivative contracts	40,578			—			28			40,606
	Commodity derivative contracts	—			1,401			—			1,401
	Netting (1)	(17,961		)	(182,955		)	—			(200,916		)
	Total derivative contracts	$	23,011		$	789		$	28		$	23,828
	Total financial instruments owned	$	24,234		$	988		$	28		$	25,250
	Other assets: Other:
	Equity security, available-for-sale	$	3,356		$	—		$	—		$	3,356
	Convertible note receivable, available-for-sale	—			—			—			—
	Total	$	27,590		$	988		$	28		$	28,606
	Liabilities
	Other liabilities: Financial instruments sold, not yet purchased:
	Equity securities	$	205		$	—		$	—		$	205
	Derivative contracts:
	Foreign exchange derivative contracts	$	14		$	182,573		$	—		$	182,587
	Fixed income derivative contracts	595			—			—			595
	Equity derivative contracts	17,567			—			—			17,567
	Commodity derivative contracts	—			1,400			—			1,400
Netting (1)	(17,961		)	(182,912		)	—			(200,873		)
Total derivative contracts	$	215		$	1,061		$	—		$	1,276
Total financial instruments sold, not yet purchased	$	420		$	1,061		$	—		$	1,481
Other liabilities: Future purchase commitment	$	—		$	—		$	3,209		$	3,209
Other liabilities: Contingent consideration	$	—		$	—		$	518		$	518
Total	$	420		$	1,061		$	3,727		$	5,208
(1)         Represents the impact of netting on a net-by-counterparty basis.
Schedule of changes in Level 3 financial assets and liabilities measured at fair value on a recurring basis	'
	Changes in Level 3 Financial Assets and Liabilities measured at fair value on a recurring basis for the three months ended September 30, 2013 are as follows:
		Beginning			Total realized			Unrealized gains			Purchases			Issuances		Sales		Settlements			Ending		Unrealized gains
		Balance			and unrealized			(losses) included													Balance at		(losses) for Level
					gains (losses)			in Other													September 30,		3 Assets /
					included in			comprehensive													2013		Liabilities
					Income (1)			(income) loss															Outstanding at
																							September 30,
																							2013
	Assets
	Other assets:
	Financial instruments owned:
	Equity derivative contracts	$	14		$	—		$	—		$	—		$	—	$	—	$	—		$	14	$	—
	Liabilities
	Other liabilities:
	Future purchase commitment	$	798		$	—		$	—		$	—		$	—	$	—	$	(798	)	$	—	$	—
	Other liabilities:
	Contingent consideration	$	204		$	(55	)	$	—		$	—		$	—	$	—	$	(159	)	$	100	$	(55	)
	(1)                   Realized and unrealized gains (losses) are reported in Other income in the Consolidated Statements of Operations.
	Changes in Level 3 Financial Assets and Liabilities measured at fair value on a recurring basis for the three months ended September 30, 2012 are as follows:
		Beginning			Total realized			Unrealized gains			Purchases			Issuances		Sales		Settlements			Ending		Unrealized gains
		Balance			and unrealized			(losses) included													Balance at		(losses) for Level
					gains (losses)			in Other													September 30,		3 Assets /
					included in			comprehensive													2012		Liabilities
					Income (1)			(income) loss															Outstanding at
																							September 30,
																							2012
	Assets
	Other assets:
	Financial instruments owned:
	Equity derivative contracts	$	2,375		$	(1,709	)	$	—		$	—		$	—	$	—	$	—		$	666	$	(1,709	)
	Other:
	Convertible note receivable, available-for-sale	$	2,662		$	(2,662	)	$	—		$	—		$	—	$	—	$	—		$	—	$	(2,662	)
	Liabilities
	Other liabilities:
	Future purchase commitment	$	5,600		$	2,081		$	(125	)	$	—		$	—	$	—	$	—		$	3,644	$	2,081
	Other liabilities:
	Contingent consideration	$	777		$	(168	)	$	—		$	—		$	—	$	—	$	(136	)	$	809	$	(168	)
	(1)                                     Realized and unrealized gains (losses) are reported in Other income in the Condensed Consolidated Statements of Operations.
	Changes in Level 3 Financial Assets and Liabilities measured at fair value on a recurring basis for the nine months ended September 30, 2013 are as follows:
		Beginning			Total realized			Unrealized gains			Purchases			Issuances		Sales		Settlements			Ending		Unrealized gains
		Balance			and unrealized			(losses) included													Balance at		(losses) for Level
					gains (losses)			in Other													September 30,		3 Assets /
					included in			comprehensive													2013		Liabilities
					Income (1)			(income) loss															Outstanding at
																							September 30,
																							2013
	Assets
	Other assets:
	Financial instruments owned:
	Equity derivative contracts	$	28		$	(14	)	$	—		$	—		$	—	$	—	$	—		$	14	$	(14	)
	Liabilities
	Other liabilities:
	Future purchase commitment	$	3,209		$	2,203		$	208		$	—		$	—	$	—	$	(798	)	$	—	$	—
	Other liabilities:
	Contingent consideration	$	518		$	(55	)	$	—		$	—		$	—	$	—	$	(473	)	$	100	$	(55	)
	(1)                                     Realized and unrealized gains (losses) are reported in Other income in the Consolidated Statements of Operations.
	Changes in Level 3 Financial Assets and Liabilities measured at fair value on a recurring basis for the nine months ended September 30, 2012 are as follows:
		Beginning			Total realized			Unrealized gains			Purchases			Issuances		Sales		Settlements			Ending		Unrealized gains
		Balance			and unrealized			(losses) included													Balance at		(losses) for Level
					gains (losses)			in Other													September 30,		3 Assets /
					included in			comprehensive													2012		Liabilities
					Income (1)			(income) loss															Outstanding at
																							September 30,
																					2012
Assets
Other assets:
Financial instruments owned:
Equity derivative contracts	$	1,937		$	(1,837	)	$	—		$	566		$	—	$	—	$	—		$	666	$	(1,837	)
Other:
Convertible note receivable, available-for-sale	$	5,362		$	(5,362	)	$	—		$	—		$	—	$	—	$	—		$	—	$	(5,362	)
Liabilities
Other liabilities:
Future purchase commitment	$	12,562		$	9,098		$	(180	)	$	—		$	—	$	—	$	—		$	3,644	$	9,098
Other liabilities:
Contingent consideration	$	1,119		$	(168	)	$	—		$	—		$	—	$	—	$	(478	)	$	809	$	(168	)
(1)                                     Realized and unrealized gains (losses) are reported in Other income in the Condensed Consolidated Statements of Operations, except  for the $5,362 impairment loss on the Convertible note receivable, available-for-sale, which was include within Other expenses in the Condensed Consolidated Statements of Operations
Schedule of significant unobservable inputs utilized by the company in the fair value measurement of Level 3 assets and liabilities measured at fair value on a recurring basis	'
		Fair Value as of			Valuation		Unobservable Input(s)		Range (Weighted
		September 30,			Technique(s)				Average) (a)
		2013
	Assets
	Equity derivative contracts	$	14		Black-Scholes Merton Model		Expected volatility		35		%
							Estimated price per share		$	8.48
		Fair Value as of			Valuation		Unobservable Input(s)		Range (Weighted
		December 31,			Technique(s)				Average) (a)
		2012
	Assets
	Equity derivative contracts	$	28		Black-Scholes-Merton Model		Expected volatility		55		%
							Estimated price per share		$	4.07	(b)
	Convertible note receivable, available-for-sale	$	—		Discounted cash flow		Estimated credit spread		19		%
					Black-Scholes-Merton Model		Expected volatility		45		%(c)
							Estimated price per convertible unit
	Liabilities
	Future purchase commitment	$	3,209		Present value of expected payments		Discount rate		15.5		%(d)
							Forecasted financial information
	(a)         As of September 30, 2013 and December 31, 2012, each asset and liability type consists of one security.
	(b)         Restated to reflect a 1-for-400 reverse split on the common stock of this investee, effective on April 23, 2013.
	(c)          To determine the estimated price per convertible unit, the Company estimated the fair value of a non-controlling interest in the entity utilizing a discounted cash flow, appropriate discount rate and combined discount for lack of control and marketability.
	(d)         The Company’s estimate of the Future Purchase Commitment as of December 31, 2012 was based on Kyte’s projected earnings through June 30, 2013. In estimating the fair value, the Company utilized post-tax projected earnings for the remaining period through June 30, 2013.

DERIVATIVE_FINANCIAL_INSTRUMEN1

DERIVATIVE FINANCIAL INSTRUMENTS (Tables)	9 Months Ended
	Sep. 30, 2013
DERIVATIVE FINANCIAL INSTRUMENTS	'
Schedule of fair values of derivative contracts on a gross and net basis	'
		September 30, 2013						December 31, 2012
	Derivatives not designated as hedging	Derivative			Derivative			Derivative			Derivative
	instruments under ASC 815-10	Assets (1)			Liabilities (2)			Assets (1)			Liabilities (2)
	Foreign exchange derivative contracts	$	20,843		$	21,646		$	182,388		$	182,628
	Commodity derivative contracts	37,755			37,756			23,656			23,680
	Fixed income derivative contracts	9,774			11,052			2,990			3,420
	Equity derivative contracts	23			9			42,811			34,460
	Total fair value of derivative contracts	$	68,395		$	70,463		$	251,845		$	244,188
	Counterparty netting	(68,112		)	(68,112		)	(227,968		)	(227,925		)
	Total fair value	$	283		$	2,351		$	23,877		$	16,263
	(1)                     Reflects futures and options on futures contracts within Receivables from brokers, dealers and clearing organizations and options and forwards contracts within Other assets.
	(2)                     Reflects futures and options on futures contracts within Payables to brokers, dealers and clearing organizations and options and forwards contracts within Other liabilities.
Schedule of outstanding long and short notional amounts on a gross basis of derivative financial instruments	'
		September 30, 2013						December 31, 2012
		Long			Short			Long			Short
	Foreign exchange derivative contracts	$	848,045		$	729,818		$	13,131,184		$	13,116,622
	Commodity derivative contracts	768,443			770,117			592,686			592,923
	Fixed income derivative contracts	5,428,807			6,395,968			5,949,603			6,057,524
	Equity derivative contracts	5,861			367			81,841			430,899
Summary of the effect of derivative contracts on the Consolidated Statements of Operations	'
	The following is a summary of the effect of derivative contracts on the Condensed Consolidated Statements of Operations for the three months ended September 30, 2013 and 2012:
		Location of Gain (Loss)		Amount of Gain (Loss) Recognized in Income on
				Derivatives
	Derivatives not designated as hedging	Recognized in Income		For the Three Months			For the Three Months
	instruments under ASC 815-10	on Derivatives		Ended September 30, 2013			Ended September 30, 2012
	Foreign exchange derivative contracts	-1		$	(500	)	$	1,463
	Commodity derivative contracts	Principal transactions		1,398			4,101
	Fixed income derivative contracts	Principal transactions		3,129			1,730
	Equity derivative contracts	-2		24			(1,424		)
	(1)         For the three months ended September 30, 2013, approximately $736 of losses on foreign exchange derivative contracts were included within Other income and approximately $236 of gains on foreign exchange derivative contracts were included within Principal transactions. For the three months ended September 30, 2012, approximately $460 of gains on foreign exchange derivative contracts were included within Other income and approximately $1,003 of gains on foreign currency options were included within Total brokerage revenues.
	(2)         For the three months ended September 30, 2013, approximately $24 of gains on equity derivative contracts were included within Principal transactions. For the three months ended September 30, 2012, approximately $1,709 of losses on equity derivative contracts were included within Other income and approximately $285 of gains on equity derivative contracts were included within Principal transactions.
	The following is a summary of the effect of derivative contracts on the Condensed Consolidated Statements of Income for the nine months ended September 30, 2013 and 2012:
		Location of Gain (Loss)		Amount of Gain (Loss) Recognized in Income on
				Derivatives
	Derivatives not designated as hedging	Recognized in Income		For the Nine Months			For the Nine Months Ended
	instruments under ASC 815-10	on Derivatives		Ended September 30, 2013			September 30, 2012
	Foreign exchange derivative contracts	-1		$	(1,926	)	$	6,334
	Commodity derivative contracts	Principal transactions		6,621			15,369
	Fixed income derivative contracts	Principal transactions		11,126			6,832
	Equity derivative contracts	-2		(164		)	(1,093		)
	(1)         For the nine months ended September 30, 2013, approximately $1,517 of losses on foreign exchange derivative contracts were included within Other income and approximately $409 of losses on foreign currency options were included within Principal transactions. For the nine months ended September 30, 2012, approximately $3,327 of gains on foreign exchange derivative contracts were included within Other income and approximately $3,007 of gains on foreign currency options were included within Principal transactions.
	(2)         For the nine months ended September 30, 2013, approximately $14 of losses on equity derivative contracts were included within Other income and approximately $150 of losses on equity derivative contracts were included within Principal transactions. For the nine months ended September 30, 2012, approximately $1,837 of losses on equity derivative contracts were included within Other income and approximately $744 of gains on equity derivative contracts were included within Principal transactions.
Summary of derivative contracts, by counterparty, including the gross amounts offset in the Condensed Consolidated Statements of Financial Position	'
	The following is a summary of derivative contracts, by counterparty, including the gross amounts offset in the Condensed Consolidated Statements of Financial Position as of September 30, 2013:
		Gross			Gross Amounts			Net Amounts of			Gross Amounts Not Offset in the
					Offset in the			Assets Offset in the			Condensed Consolidated Statements
					Condensed			Condensed			of Financial Condition
	Counterparties	Amounts of			Consolidated			Consolidated			Derivatives (2)			Cash Collateral		Net Amount
		Recognized			Statements of			Statements of						Received/
		Assets			Financial Position			Financial Position (1)						(Pledged)
	Derivative Assets:
	Counterparty A	$	20,685		$	20,416		$	269		$	—		$	—	$	269
	Counterparty B	37,755			37,755			—			—			—		—
	Counterparty C	9,941			9,941			—			—			—		—
	Counterparty D	14			—			14			—			—		14
	Total	$	68,395		$	68,112		$	283		$	—		$	—	$	283
	Derivative Liabilities:
	Counterparty A	$	21,274		$	20,416		$	858		$	—		$	—	$	858
	Counterparty B	37,756			37,755			1			—			—		1
	Counterparty C	11,301			9,941			1,360			—			—		1,360
	Counterparty E	132			—			132			—			—		132
	Total	$	70,463		$	68,112		$	2,351		$	—		$	—	$	2,351
	(1)         The total reconciles to the aggregate of total derivative contracts in the fair value measurements table and the variation margin on exchange traded futures for the respective periods; both reflected in Note 13. Derivative assets and derivative liabilities are reflected within Other assets and Other Liabilities, respectively, with the exception of futures and options on futures contracts. Futures and options on futures contracts are included within Receivables from and Payables to brokers, dealers, and clearing organizations, as applicable.
	(2)         As of September 30, 2013, the Company does not have any derivative positions under a master netting agreement that are not netted.
	The following is a summary of derivative contracts, by counterparty, including the gross amounts offset in the Condensed Consolidated Statements of Financial Position as of December 31, 2012:
		Gross			Gross Amounts			Net Amounts of			Gross Amounts Not Offset in the
					Offset in the			Assets Offset in the			Condensed Consolidated Statements
					Condensed			Condensed			of Financial Condition
								Consolidated
	Counterparties	Amounts of			Consolidated			Statements of			Derivatives (2)			Cash Collateral		Net Amount
		Recognized			Statements of			Financial Position						Received/
		Assets			Financial Position			-1						(Pledged)
	Derivative Assets:
	Counterparty A	$	183,577		$	182,955		$	622		$	—		$	—	$	622
	Counterparty B	16,987			16,938			49			—			—		49
	Counterparty C	51,087			28,075			23,012			—			—		23,012
	Counterparty D	28			—			28			—			—		28
	Counterparty F	166			—			166			—			—		166
	Total	$	251,845		$	227,968		$	23,877		$	—		$	—	$	23,877
	Derivative Liabilities:
	Counterparty A	$	183,973		$	182,912		$	1,061		$	—		$	—	$	1,061
	Counterparty B	16,938			16,938			—			—			—		—
	Counterparty C	43,277			28,075			15,202			—			—		15,202
	Total	$	244,188		$	227,925		$	16,263		$	—		$	—	$	16,263
	(1)         The total reconciles to the aggregate of total derivative contracts in the fair value measurements table and the variation margin on exchange traded futures for the respective periods; both reflected in Note 13. Derivative assets and derivative liabilities are reflected within Other assets and Other Liabilities, respectively, with the exception of futures and options on futures contracts. Futures and options on futures contracts are included within Receivables from and Payables to brokers, dealers, and clearing organizations, as applicable.
	(2)         As of December 31, 2012, the Company does not have any derivative positions under a master netting agreement that are not netted.

REGULATORY_REQUIREMENTS_Tables

REGULATORY REQUIREMENTS (Tables)	9 Months Ended
	Sep. 30, 2013
REGULATORY REQUIREMENTS	'
Schedule of aggregate regulatory capital in individually regulated entities in its operating regions	'
		Americas		EMEA		Asia
	Regulatory capital	$	25,784	$	139,041	$	35,340
	Minimum regulatory capital required	7,395		112,957		8,194
	Excess regulatory capital	$	18,389	$	26,084	$	27,146

SEGMENT_AND_GEOGRAPHIC_INFORMA1

SEGMENT AND GEOGRAPHIC INFORMATION (Tables)	9 Months Ended
	Sep. 30, 2013
SEGMENT AND GEOGRAPHIC INFORMATION	'
Schedule of financial information for the company's reportable segments	'
			Three Months Ended September 30, 2013
			Americas		EMEA		Asia		Clearing			All Other			Total
			Brokerage		Brokerage		Brokerage		and Backed
									Trading
	Total revenues		$	60,384	$	72,275	$	15,730	$	40,721		$	23,323		$	212,433
	Revenues, net of interest and transaction-based expenses		57,995		70,283		15,653		8,702			23,607			176,240
	Income (loss) before income taxes		15,515		19,078		3,438		(1,067		)	(38,120		)	(1,156		)
			Three Months Ended September 30, 2012
			Americas		EMEA		Asia		Clearing			All Other			Total
			Brokerage		Brokerage		Brokerage		and Backed
									Trading
	Total revenues		$	62,745	$	80,147	$	18,084	$	40,506		$	17,906		$	219,388
	Revenues, net of interest and transaction-based expenses		59,370		77,607		18,056		10,866			18,253			184,152
	Income (loss) before income taxes		14,392		19,889		4,722		515			(46,685		)	(7,167		)
			Nine Months Ended September 30, 2013
			Americas		EMEA		Asia		Clearing			All Other			Total
			Brokerage		Brokerage		Brokerage		and Backed
									Trading
	Total revenues		$	202,765	$	237,102	$	52,952	$	140,960		$	65,324		$	699,103
	Revenues, net of interest and transaction-based expenses		194,372		230,031		52,693		32,840			66,253			576,189
	Income (loss) before income taxes		56,139		65,756		13,257		2,492			(131,118		)	6,526
			Nine Months Ended September 30, 2012
			Americas		EMEA		Asia		Clearing			All Other			Total
			Brokerage		Brokerage		Brokerage		and Backed
									Trading
	Total revenues		$	216,674	$	263,564	$	58,010	$	121,744		$	57,301		$	717,293
	Revenues, net of interest and transaction-based expenses		205,825		255,751		57,948		35,642			58,447			613,613
	Income (loss) before income taxes		56,304		68,742		12,868		4,398			(134,143		)	8,169
Schedule of geographic information regarding revenues and long-lived assets	'
			Three Months Ended				Nine Months Ended
			September 30,				September 30,
			2013		2012		2013		2012
	Revenues:
	United States		$	61,067	$	59,511	$	203,544	$	210,671
	United Kingdom		105,471		77,575		346,166		313,209
	Other		45,895		82,302		149,393		193,413
	Total		$	212,433	$	219,388	$	699,103	$	717,293
			Three Months Ended				Nine Months Ended
			September 30,				September 30,
			2013		2012		2013		2012
	Revenues, net of interest and transaction-based expenses:
	United States		$	60,010	$	57,556	$	199,181	$	204,183
	United Kingdom		72,764		46,780		235,884		223,506
	Other		43,467		79,816		141,124		185,924
	Total		$	176,240	$	184,152	$	576,189	$	613,613
					September 30,		December 31,
					2013		2012
		Long-lived Assets, as defined:
		United States			$	49,777	$	47,675
		United Kingdom			11,510		10,536
		Other			4,767		5,239
		Total			$	66,054	$	63,450

ORGANIZATION_AND_BUSINESS_Deta

ORGANIZATION AND BUSINESS (Details) (JPI)	Sep. 30, 2013
JPI	'
Organization and Business	'
Ownership by Jersey Partners, Inc. (as a percent)	38.00%

SUMMARY_OF_SIGNIFICANT_ACCOUNT2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $)

3 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

In Thousands, unless otherwise specified

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Jul. 02, 2010

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

item

Minimum

Maximum

Kyte

Kyte

Software revenue

Software revenue

Analytics revenue

Market data subscription revenue

Market data subscription revenue

Property, equipment and leasehold improvements

Property, equipment and leasehold improvements

Computer software

Minimum

Maximum

Minimum

Maximum

Minimum

Maximum

Significant accounting policies

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of VIEs in which the company is the primary beneficiary

'

'

1

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Useful life

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'3 years

'7 years

'3 years

Amortization period of prepaid bonuses and forgivable loans

'

'

'

'

'

'2 years

'4 years

'

'

'

'

'

'

'

'

'

'

Prepaid bonuses

$25,833

'

$25,833

'

$31,847

'

'

'

'

'

'

'

'

'

'

'

'

Forgivable employee loans and advances to employees

26,009

'

26,009

'

31,655

'

'

'

'

'

'

'

'

'

'

'

'

Amortization of prepaid bonuses and forgivable employee loans

'

'

19,904

19,727

'

'

'

'

'

'

'

'

'

'

'

'

'

Carrying amount of equity method investments

37,057

'

37,057

'

26,743

'

'

'

'

'

'

'

'

'

'

'

'

Carrying amount of cost-method investments

5,064

'

5,064

'

4,671

'

'

'

'

'

'

'

'

'

'

'

'

Fair value of available-for-sale securities

4,354

'

4,354

'

3,355

'

'

'

'

'

'

'

'

'

'

'

'

Future commitment to purchase the remaining equity interest (as a percent)

'

'

'

'

'

'

'

30.00%

30.00%

'

'

'

'

'

'

'

'

Period for recognition of deferred revenue

'

'

'

'

'

'

'

'

'

'1 year

'5 years

'3 years

'1 year

'2 years

'

'

'

Net gains (losses) resulting from remeasurement of foreign currency transactions and balances

2,212

-1,113

1,757

-3,835

'

'

'

'

'

'

'

'

'

'

'

'

'

Foreign currency translation gain reclassified out of Accumulated other comprehensive income into the Consolidated Statement of Operations

$1,645

'

$1,645

'

'

'

'

'

'

'

'

'

'

'

'

'

'

RECEIVABLES_FROM_AND_PAYABLES_2

RECEIVABLES FROM AND PAYABLES TO BROKERS, DEALERS AND CLEARING ORGANIZATIONS (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Receivables from brokers, dealers and clearing organizations:	'	'
Contract value of fails to deliver	$520,516	$164,090
Receivables from and deposits with clearing organizations and financial institutions	123,048	87,348
Net pending trades	3,465	1,258
Total	647,029	252,696
Payables to brokers, dealers and clearing organizations:	'	'
Contract value of fails to receive	486,445	158,256
Payables to clearing organizations and financial institutions	26,615	6,679
Total	$513,060	$164,935

RECEIVABLES_FROM_AND_PAYABLES_3

RECEIVABLES FROM AND PAYABLES TO BROKERS, DEALERS AND CLEARING ORGANIZATIONS (Details 2) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Cash payable to clearing customers	'	'
Payables to clearing services customers	$136,215	$139,627
Cash and cash equivalents	'	'
Cash payable to clearing customers	'	'
Payables to clearing services customers	'	27,623
Cash segregated under federal and other regulations	'	'
Cash payable to clearing customers	'	'
Payables to clearing services customers	60,598	47,300
Receivables from brokers, dealers, and clearing organizations	'	'
Cash payable to clearing customers	'	'
Payables to clearing services customers	$75,617	$64,704

ACQUISITIONS_Details

ACQUISITIONS (Details) (Kyte)	0 Months Ended
In Thousands, except Share data, unless otherwise specified	Jul. 02, 2010	Jul. 02, 2010	Sep. 30, 2013
	USD ($)	GBP (£)
ACQUISITIONS	'	'	'
Equity ownership interest (as a percent)	70.00%	70.00%	70.00%
Residual percentage of ownership agreed to be purchased	30.00%	30.00%	30.00%
Future purchase commitment performance period	'3 years	'3 years	'
Deposit in escrow account	$7,592	£ 5,000	'
Contingently issuable shares	1,339,158	1,339,158	'

GOODWILL_AND_INTANGIBLE_ASSETS2

GOODWILL AND INTANGIBLE ASSETS (Details) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Goodwill	'	'
Goodwill at the beginning of the period	$267,977	'
Foreign currency translation	-206	'
Goodwill at the end of the period	267,771	267,977
Impairment of goodwill	'	0
Americas Brokerage	'	'
Goodwill	'	'
Goodwill at the end of the period	83,289	83,289
EMEA Brokerage	'	'
Goodwill	'	'
Goodwill at the beginning of the period	14,397	'
Foreign currency translation	-48	'
Goodwill at the end of the period	14,349	'
Clearing and Backed Trading	'	'
Goodwill	'	'
Goodwill at the beginning of the period	41,600	'
Foreign currency translation	-158	'
Goodwill at the end of the period	41,442	'
All other	'	'
Goodwill	'	'
Goodwill at the end of the period	$128,691	$128,691

GOODWILL_AND_INTANGIBLE_ASSETS3

GOODWILL AND INTANGIBLE ASSETS (Details 2) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Intangible Assets	'	'	'	'	'
Gross amount	$102,849	'	$102,849	'	$101,049
Accumulated amortization and foreign currency translation	60,177	'	60,177	'	52,557
Net carrying value	42,672	'	42,672	'	48,492
Intangible amortization expense	2,339	2,922	7,308	8,762	'
Expected amortization expense for the definite lived intangible assets	'	'	'	'	'
2013 (remaining three months)	2,267	'	2,267	'	'
2014	9,015	'	9,015	'	'
2015	8,909	'	8,909	'	'
2016	6,878	'	6,878	'	'
2017	3,494	'	3,494	'	'
Thereafter	12,109	'	12,109	'	'
Customer relationships	'	'	'	'	'
Intangible Assets	'	'	'	'	'
Gross amount	78,896	'	78,896	'	77,426
Accumulated amortization and foreign currency translation	41,492	'	41,492	'	35,597
Net carrying value	37,404	'	37,404	'	41,829
Trade names	'	'	'	'	'
Intangible Assets	'	'	'	'	'
Gross amount	8,951	'	8,951	'	8,951
Accumulated amortization and foreign currency translation	6,565	'	6,565	'	6,181
Net carrying value	2,386	'	2,386	'	2,770
Core technology	'	'	'	'	'
Intangible Assets	'	'	'	'	'
Gross amount	6,400	'	6,400	'	6,400
Accumulated amortization and foreign currency translation	6,400	'	6,400	'	5,835
Net carrying value	'	'	'	'	565
Non-compete agreements	'	'	'	'	'
Intangible Assets	'	'	'	'	'
Gross amount	4,204	'	4,204	'	3,874
Accumulated amortization and foreign currency translation	3,806	'	3,806	'	3,656
Net carrying value	398	'	398	'	218
Favorable lease agreements	'	'	'	'	'
Intangible Assets	'	'	'	'	'
Gross amount	620	'	620	'	620
Accumulated amortization and foreign currency translation	560	'	560	'	500
Net carrying value	60	'	60	'	120
Patents	'	'	'	'	'
Intangible Assets	'	'	'	'	'
Gross amount	3,131	'	3,131	'	3,131
Accumulated amortization and foreign currency translation	1,097	'	1,097	'	723
Net carrying value	2,034	'	2,034	'	2,408
Other	'	'	'	'	'
Intangible Assets	'	'	'	'	'
Gross amount	647	'	647	'	647
Accumulated amortization and foreign currency translation	257	'	257	'	65
Net carrying value	$390	'	$390	'	$582

OTHER_ASSETS_AND_OTHER_LIABILI2

OTHER ASSETS AND OTHER LIABILITIES (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Other assets	'	'
Deferred tax assets	$51,046	$41,567
Investments accounted for under the cost method and equity method	42,121	31,414
Forgivable employee loans and advances to employees	26,009	31,655
Prepaid bonuses	25,833	31,847
Deferred financing fees	6,942	8,074
Financial instruments owned	2,981	25,250
Software inventory, net	2,905	4,615
Other	28,726	28,774
Total Other assets	$186,563	$203,196

OTHER_ASSETS_AND_OTHER_LIABILI3

OTHER ASSETS AND OTHER LIABILITIES (Details 2) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Other liabilities	'	'
Payroll related liabilities	$27,685	$15,418
Deferred revenues	9,251	7,247
Unrecognized tax benefits	8,956	8,957
Deferred tax liabilities	6,715	7,943
Financial instruments sold, not yet purchased	1,567	1,481
Future purchase commitment and contingent consideration liabilities	100	3,727
Other	31,237	38,801
Total Other liabilities	$85,511	$83,574

SHORTTERM_BORROWINGS_AND_LONGT2

SHORT-TERM BORROWINGS AND LONG-TERM OBLIGATIONS (Details) (USD $)	0 Months Ended			1 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Jul. 19, 2013	Jun. 26, 2013	Jan. 19, 2013	Jul. 31, 2011	Sep. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Dec. 21, 2011
SHORT-TERM BORROWINGS AND LONG-TERM OBLIGATIONS	'	'	'	'	'	'	'	'
Long-term obligations	'	'	'	'	$240,000	'	$250,000	'
Loans pursuant to Credit Agreement	'	'	'	'	10,000	'	'	'
Total	'	'	'	'	250,000	'	250,000	'
Unamortized deferred financing fees	'	'	'	'	6,942	'	8,074	'
8.375% Senior Notes due 2018	'	'	'	'	'	'	'	'
SHORT-TERM BORROWINGS AND LONG-TERM OBLIGATIONS	'	'	'	'	'	'	'	'
Long-term obligations	'	'	'	'	240,000	'	250,000	'
Carrying Amount	'	'	'	'	240,000	'	250,000	'
Fair Value	'	'	'	'	242,700	'	220,720	'
Interest rate (as a percent)	'	'	'	8.38%	8.38%	'	'	'
Increase in per annum interest rate (as a percent)	0.005	0.0025	0.005	'	0.02	'	'	'
Aggregate additional interest per annum	'	'	'	'	4,800	'	'	'
Principal amount	'	'	'	'	'	10,000	'	'
Aggregate purchase price	'	'	'	'	'	9,602	'	'
Aggregate principal amount	'	'	'	250,000	'	'	'	'
Price of notes as percentage of principal amount	'	'	'	100.00%	'	'	'	'
Transaction costs	'	'	'	9,100	'	'	'	'
Aggregate principal amount of notes exchanged for notes registered under the Securities Act	'	'	'	'	'	'	'	250,000
Unamortized deferred financing fees	'	'	'	'	5,981	'	7,205	'
Credit Agreement	'	'	'	'	'	'	'	'
SHORT-TERM BORROWINGS AND LONG-TERM OBLIGATIONS	'	'	'	'	'	'	'	'
Weighted average interest rate (as a percent)	'	'	'	'	3.43%	'	'	'
Unamortized deferred financing fees	'	'	'	'	961	'	869	'
Maximum borrowings	'	'	'	'	'	75,000	129,500	'
Annualized rate of interest	'	'	'	'	'one-month LIBOR	'	'	'
Credit Agreement | Maturity by December 2013	'	'	'	'	'	'	'	'
SHORT-TERM BORROWINGS AND LONG-TERM OBLIGATIONS	'	'	'	'	'	'	'	'
Maximum borrowings	'	'	'	'	'	18,750	'	'
Credit Agreement | Maturity by December 2015	'	'	'	'	'	'	'	'
SHORT-TERM BORROWINGS AND LONG-TERM OBLIGATIONS	'	'	'	'	'	'	'	'
Maximum borrowings	'	'	'	'	'	56,250	'	'
Letters of credit	'	'	'	'	'	'	'	'
SHORT-TERM BORROWINGS AND LONG-TERM OBLIGATIONS	'	'	'	'	'	'	'	'
Maximum borrowings	'	'	'	'	'	$50,000	$50,000	'

STOCKHOLDERS_EQUITY_Details

STOCKHOLDERS' EQUITY (Details) (USD $)	0 Months Ended					9 Months Ended		3 Months Ended	9 Months Ended
In Thousands, except Share data, unless otherwise specified	Aug. 30, 2013	31-May-13	Aug. 31, 2012	31-May-12	Mar. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2012	Sep. 30, 2012
								2007 Repurchase program	2007 Repurchase program
Shares of common stock repurchased	'	'	'	'	'	'	'	1,413,067	3,107,469
Average price of shares of common stock repurchased (in dollars per share)	'	'	'	'	'	'	'	$3.25	$3.17
Total cost of shares repurchased including sales commissions	'	'	'	'	'	'	'	$4,641	$9,939
Cash dividend paid (in dollars per share)	$0.05	$0.05	$0.05	$0.05	$0.05	'	'	'	'
Total cash dividend paid	$6,096	$5,999	$5,873	$5,991	$5,897	$12,095	$17,761	'	'

LOSS_EARNINGS_PER_SHARE_Detail

(LOSS) EARNINGS PER SHARE (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Basic (loss) earnings per share	'	'	'	'
GFI's net (loss) income	($461)	($8,693)	$10,904	$1,419
Weighted average common shares outstanding	120,331,179	115,541,373	118,138,756	116,073,488
Basic (loss) earnings per share (in dollars per share)	$0	($0.08)	$0.09	$0.01
Diluted (loss) earnings per share	'	'	'	'
GFI's net (loss) income	($461)	($8,693)	$10,904	$1,419
Weighted average common shares outstanding	120,331,179	115,541,373	118,138,756	116,073,488
Effect of dilutive options, RSUs and other contingently issuable shares	'	'	8,719,703	7,496,622
Weighted average shares outstanding and common stock equivalents	120,331,179	115,541,373	126,858,459	123,570,110
Diluted (loss) earnings per share (in dollars per share)	$0	($0.08)	$0.09	$0.01
Contingently issuable shares included in computation of diluted earnings per share	'	'	2,736,121	3,682,916
Contingently issuable shares excluded from computation of diluted loss per share as a result of net loss	1,637,673	3,682,916	'	'
RSUs	'	'	'	'
EARNINGS (LOSS) PER SHARE	'	'	'	'
Antidilutive securities excluded from computation of earnings per share (in shares)	259,380	7,341,891	2,660,905	8,433,605
Securities excluded from computation of diluted loss per share as a result of net loss (in shares)	6,320,799	3,130,644	'	'
Options	'	'	'	'
EARNINGS (LOSS) PER SHARE	'	'	'	'
Antidilutive securities excluded from computation of earnings per share (in shares)	69,476	77,476	69,476	77,476
Securities excluded from computation of diluted loss per share as a result of net loss (in shares)	99,362	39,715	'	'

SHAREBASED_COMPENSATION_Detail

SHARE-BASED COMPENSATION (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
RSUs	'	'	'	'
Total compensation expense and related income tax benefits	'	'	'	'
Compensation expense	$6,870	$7,751	$22,372	$24,653
Income tax benefits	1,913	2,359	6,655	7,506
Total unrecognized compensation cost	56,057	'	56,057	'
Weighted average period over which unrecognized compensation cost is expected to be recognized	'	'	'1 year 8 months 16 days	'
Total fair value of shares vested	'	'	28,395	30,021
Stock option	'	'	'	'
Total compensation expense and related income tax benefits	'	'	'	'
Number of plans	2	'	2	'
Expiration term of options	'	'	'10 years	'
Weighted Average Exercise Price	'	'	'	'
Unrecognized compensation cost	$0	$0	$0	$0
2008 Equity Incentive Plan	'	'	'	'
SHARE-BASED COMPENSATION	'	'	'	'
Shares of common stock available for future grants of awards	8,579,962	'	8,579,962	'
2008 Equity Incentive Plan and 2004 Equity Incentive Plan | RSUs	'	'	'	'
RSUs	'	'	'	'
Outstanding at the beginning of the period (in shares)	'	'	19,353,382	'
Granted (in shares)	'	'	6,554,167	'
Vested (in shares)	'	'	-6,338,258	'
Cancelled (in shares)	'	'	-885,739	'
Outstanding at the end of the period (in shares)	18,683,552	'	18,683,552	'
Weighted-Average Grant Date Fair Value	'	'	'	'
Outstanding at the beginning of the period (in dollars per share)	'	'	$4.27	'
Granted (in dollars per share)	'	'	$3.71	$3.56
Vested (in dollars per share)	'	'	$4.48	'
Cancelled (in dollars per share)	'	'	$4.01	'
Outstanding at the end of the period (in dollars per share)	$4.02	'	$4.02	'
GFI Group 2002 Plan | Stock option	'	'	'	'
SHARE-BASED COMPENSATION	'	'	'	'
Shares of common stock available for future grants of awards	0	'	0	'
Options	'	'	'	'
Outstanding at the beginning of the period (in shares)	'	'	575,220	'
Exercised (in shares)	'	'	-205,952	'
Cancelled (in shares)	'	'	-10,104	'
Expired (in shares)	'	'	-3,156	'
Outstanding at the end of the period (in shares)	356,008,000	'	356,008,000	'
Weighted Average Exercise Price	'	'	'	'
Outstanding at the beginning of the period (in dollars per share)	'	'	$3.29	'
Exercised (in dollars per share)	'	'	$2.97	'
Cancelled (in dollars per share)	'	'	$2.97	'
Expired (in dollars per share)	'	'	$4.78	'
Outstanding at the end of the period (in dollars per share)	$3.42	'	$3.42	'
GFInet 2000 Plan | Stock option	'	'	'	'
SHARE-BASED COMPENSATION	'	'	'	'
Shares of common stock available for future grants of awards	0	'	0	'
Options	'	'	'	'
Outstanding at the beginning of the period (in shares)	'	'	16,844	'
Exercised (in shares)	'	'	-16,844	'
Weighted Average Exercise Price	'	'	'	'
Outstanding at the beginning of the period (in dollars per share)	'	'	$2.97	'
Exercised (in dollars per share)	'	'	$2.97	'

COMMITMENTS_AND_CONTINGENCIES_

COMMITMENTS AND CONTINGENCIES (Details) (USD $)	Sep. 30, 2013
In Thousands, unless otherwise specified
Market data	'
Purchase Obligations	'
Purchase commitments	$24,801
Purchase commitments due within next twelve months	18,369
Purchase commitments due between one to three years	6,278
Purchase commitments due between three to five years	154
Network implementations	'
Purchase Obligations	'
Purchase commitments	6,634
Hosting and software license agreements	'
Purchase Obligations	'
Purchase commitments	1,126
Network implementations and hosting and software license agreements	'
Purchase Obligations	'
Purchase commitments due within next twelve months	$5,397

FAIR_VALUE_OF_FINANCIAL_INSTRU2

FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) (Kyte, USD $)	Sep. 30, 2013	Jul. 02, 2010
In Thousands, unless otherwise specified
Kyte	'	'
Valuation Techniques	'	'
Equity ownership interest (as a percent)	70.00%	70.00%
Residual percentage of ownership agreed to be acquired	30.00%	30.00%
Purchase price for residual equity interest	$0	'

FAIR_VALUE_OF_FINANCIAL_INSTRU3

FAIR VALUE OF FINANCIAL INSTRUMENTS (Details 2) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Assets	'	'
Other assets: Financial instruments owned	$2,981	$25,250
Liabilities	'	'
Other liabilities: Financial instruments sold, not yet purchased	1,567	1,481
Margin on net long derivative contracts related to exchange traded futures included within receivables from brokers, dealers and clearing organizations	'	49
Margin on net short derivative contracts related to exchange traded futures included within receivables from brokers, dealers and clearing organizations	877	14,986
Fair value measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)	'	'
Assets	'	'
Other assets: Financial instruments owned	2,521	24,234
Other assets: Other:	'	'
Equity security, available-for-sale	4,354	3,356
Total	6,875	27,590
Liabilities	'	'
Other liabilities: Financial instruments sold, not yet purchased	577	420
Total	577	420
Fair value measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity securities	'	'
Assets	'	'
Other assets: Financial instruments owned	2,521	1,223
Liabilities	'	'
Other liabilities: Financial instruments sold, not yet purchased	24	205
Fair value measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Foreign government bonds	'	'
Liabilities	'	'
Other liabilities: Financial instruments sold, not yet purchased	68	'
Fair value measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Derivative contracts	'	'
Assets	'	'
Other assets: Financial instruments owned	'	23,011
Netting	-1,212	-17,961
Liabilities	'	'
Other liabilities: Financial instruments sold, not yet purchased	485	215
Netting	-1,212	-17,961
Fair value measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Foreign exchange derivative contracts	'	'
Assets	'	'
Other assets: Financial instruments owned	4	'
Liabilities	'	'
Other liabilities: Financial instruments sold, not yet purchased	91	14
Fair value measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed income derivative contracts	'	'
Assets	'	'
Other assets: Financial instruments owned	1,208	394
Liabilities	'	'
Other liabilities: Financial instruments sold, not yet purchased	1,606	595
Fair value measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity derivative contracts	'	'
Assets	'	'
Other assets: Financial instruments owned	'	40,578
Liabilities	'	'
Other liabilities: Financial instruments sold, not yet purchased	'	17,567
Fair value measured on a recurring basis | Significant Other Observable Inputs (Level 2)	'	'
Assets	'	'
Other assets: Financial instruments owned	446	988
Other assets: Other:	'	'
Total	446	988
Liabilities	'	'
Other liabilities: Financial instruments sold, not yet purchased	990	1,061
Total	990	1,061
Fair value measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Equity securities	'	'
Assets	'	'
Other assets: Financial instruments owned	177	199
Fair value measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Derivative contracts	'	'
Assets	'	'
Other assets: Financial instruments owned	269	789
Netting	-20,416	-182,955
Liabilities	'	'
Other liabilities: Financial instruments sold, not yet purchased	990	1,061
Netting	-20,416	-182,912
Fair value measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Foreign exchange derivative contracts	'	'
Assets	'	'
Other assets: Financial instruments owned	20,685	182,343
Liabilities	'	'
Other liabilities: Financial instruments sold, not yet purchased	21,406	182,573
Fair value measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Commodity derivative contracts	'	'
Assets	'	'
Other assets: Financial instruments owned	'	1,401
Liabilities	'	'
Other liabilities: Financial instruments sold, not yet purchased	'	1,400
Fair value measured on a recurring basis | Significant Unobservable Inputs (Level 3)	'	'
Assets	'	'
Other assets: Financial instruments owned	14	28
Other assets: Other:	'	'
Total	14	28
Liabilities	'	'
Other liabilities: Future purchase commitment	'	3,209
Other liabilities: Contingent consideration	100	518
Total	100	3,727
Fair value measured on a recurring basis | Significant Unobservable Inputs (Level 3) | Derivative contracts	'	'
Assets	'	'
Other assets: Financial instruments owned	14	28
Fair value measured on a recurring basis | Significant Unobservable Inputs (Level 3) | Equity derivative contracts	'	'
Assets	'	'
Other assets: Financial instruments owned	14	28
Other assets: Other:	'	'
Total	14	28
Fair value measured on a recurring basis | Total	'	'
Assets	'	'
Other assets: Financial instruments owned	2,981	25,250
Other assets: Other:	'	'
Equity security, available-for-sale	4,354	3,356
Total	7,335	28,606
Liabilities	'	'
Other liabilities: Financial instruments sold, not yet purchased	1,567	1,481
Other liabilities: Future purchase commitment	'	3,209
Other liabilities: Contingent consideration	100	518
Total	1,667	5,208
Fair value measured on a recurring basis | Total | Equity securities	'	'
Assets	'	'
Other assets: Financial instruments owned	2,698	1,422
Liabilities	'	'
Other liabilities: Financial instruments sold, not yet purchased	24	205
Fair value measured on a recurring basis | Total | Foreign government bonds	'	'
Liabilities	'	'
Other liabilities: Financial instruments sold, not yet purchased	68	'
Fair value measured on a recurring basis | Total | Derivative contracts	'	'
Assets	'	'
Other assets: Financial instruments owned	283	23,828
Netting	-21,628	-200,916
Liabilities	'	'
Other liabilities: Financial instruments sold, not yet purchased	1,475	1,276
Netting	-21,628	-200,873
Fair value measured on a recurring basis | Total | Foreign exchange derivative contracts	'	'
Assets	'	'
Other assets: Financial instruments owned	20,689	182,343
Liabilities	'	'
Other liabilities: Financial instruments sold, not yet purchased	21,497	182,587
Fair value measured on a recurring basis | Total | Fixed income derivative contracts	'	'
Assets	'	'
Other assets: Financial instruments owned	1,208	394
Liabilities	'	'
Other liabilities: Financial instruments sold, not yet purchased	1,606	595
Fair value measured on a recurring basis | Total | Equity derivative contracts	'	'
Assets	'	'
Other assets: Financial instruments owned	14	40,606
Liabilities	'	'
Other liabilities: Financial instruments sold, not yet purchased	'	17,567
Fair value measured on a recurring basis | Total | Commodity derivative contracts	'	'
Assets	'	'
Other assets: Financial instruments owned	'	1,401
Liabilities	'	'
Other liabilities: Financial instruments sold, not yet purchased	'	$1,400

FAIR_VALUE_OF_FINANCIAL_INSTRU4

FAIR VALUE OF FINANCIAL INSTRUMENTS (Details 3) (Recurring basis, USD $)	3 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Jun. 30, 2013
Equity derivative contracts	'	'	'	'
Changes in Level 3 Financial Assets measured at fair value	'	'	'	'
Beginning Balance	$2,375	$28	$1,937	$14
Total realized and unrealized gains (losses) included in Income	-1,709	-14	-1,837	'
Purchases	'	'	566	'
Ending Balance	666	14	666	14
Unrealized gains (losses) for Level 3 Assets outstanding at end of the period	-1,709	-14	-1,837	'
Convertible note receivable, available-for-sale	'	'	'	'
Changes in Level 3 Financial Assets measured at fair value	'	'	'	'
Beginning Balance	2,662	'	5,362	'
Total realized and unrealized gains (losses) included in Income	-2,662	'	-5,362	'
Unrealized gains (losses) for Level 3 Assets outstanding at end of the period	($2,662)	'	($5,362)	'

FAIR_VALUE_OF_FINANCIAL_INSTRU5

FAIR VALUE OF FINANCIAL INSTRUMENTS (Details 4) (Recurring basis, USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Future purchase commitment	'	'	'	'
Changes in Level 3 Financial Liabilities measured at fair value	'	'	'	'
Beginning Balance	$798	$5,600	$3,209	$12,562
Total realized and unrealized gains (losses) included in Income	'	2,081	2,203	9,098
Unrealized gains (losses) included in Other Comprehensive (income) loss	'	-125	208	-180
Settlements	-798	'	-798	'
Ending Balance	'	3,644	'	3,644
Unrealized gains (losses) for Level 3 Liabilities outstanding at end of the period	'	2,081	'	9,098
Contingent consideration	'	'	'	'
Changes in Level 3 Financial Liabilities measured at fair value	'	'	'	'
Beginning Balance	204	777	518	1,119
Total realized and unrealized gains (losses) included in Income	-55	-168	-55	-168
Settlements	-159	-136	-473	-478
Ending Balance	100	809	100	809
Unrealized gains (losses) for Level 3 Liabilities outstanding at end of the period	($55)	($168)	($55)	($168)

FAIR_VALUE_OF_FINANCIAL_INSTRU6

FAIR VALUE OF FINANCIAL INSTRUMENTS (Details 5) (Fair value measured on a recurring basis, Significant Unobservable Inputs (Level 3), USD $)	0 Months Ended	9 Months Ended	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Apr. 23, 2013	Sep. 30, 2013	Dec. 31, 2012
Fair value, Unobservable Input	'	'	'
Fair Value, Assets	'	$14	$28
Fair Value, Liabilities	'	100	3,727
Future Purchase Commitment	'	'	'
Fair value, Unobservable Input	'	'	'
Fair Value, Liabilities	'	'	3,209
Future Purchase Commitment | Present value of expected payments	'	'	'
Unobservable Input(s)	'	'	'
Discount rate (as a percent)	'	'	15.50%
Equity derivative contracts	'	'	'
Fair value, Unobservable Input	'	'	'
Fair Value, Assets	'	$14	$28
Equity derivative contracts | Black-Scholes-Merton Model	'	'	'
Unobservable Input(s)	'	'	'
Expected volatility (as a percent)	'	35.00%	55.00%
Estimated price per share (in dollars per share)	'	$8.48	$4.07
Reverse split ratio of common stock of investee	0.0025	'	'
Convertible note receivable, available-for-sale | Black-Scholes-Merton Model	'	'	'
Unobservable Input(s)	'	'	'
Expected volatility (as a percent)	'	'	45.00%
Convertible note receivable, available-for-sale | Discounted cash flow	'	'	'
Unobservable Input(s)	'	'	'
Estimated credit spread (as a percent)	'	'	19.00%

DERIVATIVE_FINANCIAL_INSTRUMEN2

DERIVATIVE FINANCIAL INSTRUMENTS (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Derivative Assets	'	'
Total fair value of derivative contracts	$68,395	$251,845
Counterparty netting	-68,112	-227,968
Derivative Liabilities	'	'
Total fair value of derivative contracts	70,463	244,188
Counterparty netting	-68,112	-227,925
Derivatives not designated as hedging instruments	'	'
Derivative Assets	'	'
Total fair value of derivative contracts	68,395	251,845
Counterparty netting	-68,112	-227,968
Total fair value	283	23,877
Derivative Liabilities	'	'
Total fair value of derivative contracts	70,463	244,188
Counterparty netting	-68,112	-227,925
Total fair value	2,351	16,263
Foreign exchange derivative contracts | Derivatives not designated as hedging instruments	'	'
Derivative Assets	'	'
Total fair value of derivative contracts	20,843	182,388
Derivative Liabilities	'	'
Total fair value of derivative contracts	21,646	182,628
Foreign exchange derivative contracts | Derivatives designated as hedging instruments	'	'
Derivative Liabilities	'	'
Notional value of derivative	67,685	96,234
Euro-denominated and Swiss franc-denominated balance sheet positions | Derivatives designated as hedging instruments	'	'
Derivative Liabilities	'	'
Notional value of derivative	27,105	26,390
Commodity derivative contracts | Derivatives not designated as hedging instruments	'	'
Derivative Assets	'	'
Total fair value of derivative contracts	37,755	23,656
Derivative Liabilities	'	'
Total fair value of derivative contracts	37,756	23,680
Fixed income derivative contracts | Derivatives not designated as hedging instruments	'	'
Derivative Assets	'	'
Total fair value of derivative contracts	9,774	2,990
Derivative Liabilities	'	'
Total fair value of derivative contracts	11,052	3,420
Equity derivative contracts | Derivatives not designated as hedging instruments	'	'
Derivative Assets	'	'
Total fair value of derivative contracts	23	42,811
Derivative Liabilities	'	'
Total fair value of derivative contracts	$9	$34,460

DERIVATIVE_FINANCIAL_INSTRUMEN3

DERIVATIVE FINANCIAL INSTRUMENTS (Details 2) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Foreign exchange derivative contracts | Long	'	'
Notional amount of derivatives	'	'
Notional amount	$848,045	$13,131,184
Foreign exchange derivative contracts | Short	'	'
Notional amount of derivatives	'	'
Notional amount	729,818	13,116,622
Commodity derivative contracts | Long	'	'
Notional amount of derivatives	'	'
Notional amount	768,443	592,686
Commodity derivative contracts | Short	'	'
Notional amount of derivatives	'	'
Notional amount	770,117	592,923
Fixed income derivative contracts | Long	'	'
Notional amount of derivatives	'	'
Notional amount	5,428,807	5,949,603
Fixed income derivative contracts | Short	'	'
Notional amount of derivatives	'	'
Notional amount	6,395,968	6,057,524
Equity derivative contracts | Long	'	'
Notional amount of derivatives	'	'
Notional amount	5,861	81,841
Equity derivative contracts | Short	'	'
Notional amount of derivatives	'	'
Notional amount	$367	$430,899

DERIVATIVE_FINANCIAL_INSTRUMEN4

DERIVATIVE FINANCIAL INSTRUMENTS (Details 3) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Foreign exchange derivative contracts | Principal transactions	'	'	'	'
Effect of derivative contracts on the Condensed Consolidated Statements	'	'	'	'
Amount of Gain (Loss) Recognized in Income on Derivatives	$236	'	($409)	$3,007
Foreign exchange derivative contracts | Other income (loss)	'	'	'	'
Effect of derivative contracts on the Condensed Consolidated Statements	'	'	'	'
Amount of Gain (Loss) Recognized in Income on Derivatives	-736	460	-1,517	3,327
Foreign exchange derivative contracts | Total brokerage revenues	'	'	'	'
Effect of derivative contracts on the Condensed Consolidated Statements	'	'	'	'
Amount of Gain (Loss) Recognized in Income on Derivatives	'	1,003	'	'
Foreign exchange derivative contracts | Derivatives not designated as hedging instruments	'	'	'	'
Effect of derivative contracts on the Condensed Consolidated Statements	'	'	'	'
Amount of Gain (Loss) Recognized in Income on Derivatives	-500	1,463	-1,926	6,334
Commodity derivative contracts | Derivatives not designated as hedging instruments | Principal transactions	'	'	'	'
Effect of derivative contracts on the Condensed Consolidated Statements	'	'	'	'
Amount of Gain (Loss) Recognized in Income on Derivatives	1,398	4,101	6,621	15,369
Fixed income derivative contracts | Derivatives not designated as hedging instruments | Principal transactions	'	'	'	'
Effect of derivative contracts on the Condensed Consolidated Statements	'	'	'	'
Amount of Gain (Loss) Recognized in Income on Derivatives	3,129	1,730	11,126	6,832
Equity derivative contracts | Principal transactions	'	'	'	'
Effect of derivative contracts on the Condensed Consolidated Statements	'	'	'	'
Amount of Gain (Loss) Recognized in Income on Derivatives	24	285	-150	744
Equity derivative contracts | Other income (loss)	'	'	'	'
Effect of derivative contracts on the Condensed Consolidated Statements	'	'	'	'
Amount of Gain (Loss) Recognized in Income on Derivatives	'	-1,709	-14	-1,837
Equity derivative contracts | Derivatives not designated as hedging instruments	'	'	'	'
Effect of derivative contracts on the Condensed Consolidated Statements	'	'	'	'
Amount of Gain (Loss) Recognized in Income on Derivatives	$24	($1,424)	($164)	($1,093)

DERIVATIVE_FINANCIAL_INSTRUMEN5

DERIVATIVE FINANCIAL INSTRUMENTS (Details 4) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Derivative Assets:	'	'
Gross Amounts of Recognized Assets	$68,395	$251,845
Gross Amounts Offset in the Condensed Consolidated Statements of Financial Position	68,112	227,968
Net Amounts of Assets Offset in the Condensed Consolidated Statements of Financial Position	283	23,877
Derivative Liabilities:	'	'
Gross Amounts of Recognized Liabilities	70,463	244,188
Gross Amounts Offset in the Condensed Consolidated Statements of Financial Position	68,112	227,925
Net Amounts of Liabilities Offset in the Condensed Consolidated Statements of Financial Position	2,351	16,263
Counterparty A	'	'
Derivative Assets:	'	'
Gross Amounts of Recognized Assets	20,685	183,577
Gross Amounts Offset in the Condensed Consolidated Statements of Financial Position	20,416	182,955
Net Amounts of Assets Offset in the Condensed Consolidated Statements of Financial Position	269	622
Derivative Liabilities:	'	'
Gross Amounts of Recognized Liabilities	21,274	183,973
Gross Amounts Offset in the Condensed Consolidated Statements of Financial Position	20,416	182,912
Net Amounts of Liabilities Offset in the Condensed Consolidated Statements of Financial Position	858	1,061
Counterparty B	'	'
Derivative Assets:	'	'
Gross Amounts of Recognized Assets	37,755	16,987
Gross Amounts Offset in the Condensed Consolidated Statements of Financial Position	37,755	16,938
Net Amounts of Assets Offset in the Condensed Consolidated Statements of Financial Position	'	49
Derivative Liabilities:	'	'
Gross Amounts of Recognized Liabilities	37,756	16,938
Gross Amounts Offset in the Condensed Consolidated Statements of Financial Position	37,755	16,938
Net Amounts of Liabilities Offset in the Condensed Consolidated Statements of Financial Position	1	'
Counterparty C	'	'
Derivative Assets:	'	'
Gross Amounts of Recognized Assets	9,941	51,087
Gross Amounts Offset in the Condensed Consolidated Statements of Financial Position	9,941	28,075
Net Amounts of Assets Offset in the Condensed Consolidated Statements of Financial Position	'	23,012
Derivative Liabilities:	'	'
Gross Amounts of Recognized Liabilities	11,301	43,277
Gross Amounts Offset in the Condensed Consolidated Statements of Financial Position	9,941	28,075
Net Amounts of Liabilities Offset in the Condensed Consolidated Statements of Financial Position	1,360	15,202
Counterparty D	'	'
Derivative Assets:	'	'
Gross Amounts of Recognized Assets	14	28
Net Amounts of Assets Offset in the Condensed Consolidated Statements of Financial Position	14	28
Counterparty E	'	'
Derivative Liabilities:	'	'
Gross Amounts of Recognized Liabilities	132	'
Net Amounts of Liabilities Offset in the Condensed Consolidated Statements of Financial Position	132	'
Counterparty F	'	'
Derivative Assets:	'	'
Gross Amounts of Recognized Assets	'	166
Net Amounts of Assets Offset in the Condensed Consolidated Statements of Financial Position	'	$166

VARIABLE_INTEREST_ENTITIES_Det

VARIABLE INTEREST ENTITIES (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Non-consolidated Variable Interest Entities | VIEs in the form of direct equity interests and a convertible note	'	'
VARIABLE INTEREST ENTITIES	'	'
Carrying Amount of Assets	$3,511	$4,438
Maximum exposure to loss	3,511	4,438
Non-consolidated Variable Interest Entities | VIEs in the form of trading margin accounts	'	'
VARIABLE INTEREST ENTITIES	'	'
Carrying Amount of Assets	1,596	9,784
Maximum exposure to loss	1,596	10,703
Consolidated Variable Interest Entities	'	'
VARIABLE INTEREST ENTITIES	'	'
Total assets of consolidated VIE	9,550	6,428
Total liabilities of consolidated VIE	$3,433	$1,558

REGULATORY_REQUIREMENTS_Detail

REGULATORY REQUIREMENTS (Details) (USD $)	Sep. 30, 2013
In Thousands, unless otherwise specified
Americas	'
REGULATORY REQUIREMENTS	'
Regulatory capital	$25,784
Minimum regulatory capital required	7,395
Excess regulatory capital	18,389
EMEA	'
REGULATORY REQUIREMENTS	'
Regulatory capital	139,041
Minimum regulatory capital required	112,957
Excess regulatory capital	26,084
Asia	'
REGULATORY REQUIREMENTS	'
Regulatory capital	35,340
Minimum regulatory capital required	8,194
Excess regulatory capital	$27,146

SEGMENT_AND_GEOGRAPHIC_INFORMA2

SEGMENT AND GEOGRAPHIC INFORMATION (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
			item
SEGMENT AND GEOGRAPHIC INFORMATION	'	'	'	'
Number of operating segments	'	'	5	'
Number of broad product categories	'	'	4	'
SEGMENT AND GEOGRAPHIC INFORMATION	'	'	'	'
Total revenues	$212,433	$219,388	$699,103	$717,293
Revenues, net of interest and transaction-based expenses	176,240	184,152	576,189	613,613
Income (loss) before income taxes	-1,156	-7,167	6,526	8,169
Americas Brokerage	'	'	'	'
SEGMENT AND GEOGRAPHIC INFORMATION	'	'	'	'
Total revenues	60,384	62,745	202,765	216,674
Revenues, net of interest and transaction-based expenses	57,995	59,370	194,372	205,825
Income (loss) before income taxes	15,515	14,392	56,139	56,304
EMEA Brokerage	'	'	'	'
SEGMENT AND GEOGRAPHIC INFORMATION	'	'	'	'
Total revenues	72,275	80,147	237,102	263,564
Revenues, net of interest and transaction-based expenses	70,283	77,607	230,031	255,751
Income (loss) before income taxes	19,078	19,889	65,756	68,742
Asia Brokerage	'	'	'	'
SEGMENT AND GEOGRAPHIC INFORMATION	'	'	'	'
Total revenues	15,730	18,084	52,952	58,010
Revenues, net of interest and transaction-based expenses	15,653	18,056	52,693	57,948
Income (loss) before income taxes	3,438	4,722	13,257	12,868
Clearing and Backed Trading	'	'	'	'
SEGMENT AND GEOGRAPHIC INFORMATION	'	'	'	'
Total revenues	40,721	40,506	140,960	121,744
Revenues, net of interest and transaction-based expenses	8,702	10,866	32,840	35,642
Income (loss) before income taxes	-1,067	515	2,492	4,398
All other	'	'	'	'
SEGMENT AND GEOGRAPHIC INFORMATION	'	'	'	'
Total revenues	23,323	17,906	65,324	57,301
Revenues, net of interest and transaction-based expenses	23,607	18,253	66,253	58,447
Income (loss) before income taxes	($38,120)	($46,685)	($131,118)	($134,143)

SEGMENT_AND_GEOGRAPHIC_INFORMA3

SEGMENT AND GEOGRAPHIC INFORMATION (Details 2) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
SEGMENT AND GEOGRAPHIC INFORMATION	'	'	'	'	'
Revenues:	$212,433	$219,388	$699,103	$717,293	'
Revenues, net of interest and transaction-based expenses:	176,240	184,152	576,189	613,613	'
Long-lived Assets, as defined:	66,054	'	66,054	'	63,450
United States	'	'	'	'	'
SEGMENT AND GEOGRAPHIC INFORMATION	'	'	'	'	'
Revenues:	61,067	59,511	203,544	210,671	'
Revenues, net of interest and transaction-based expenses:	60,010	57,556	199,181	204,183	'
Long-lived Assets, as defined:	49,777	'	49,777	'	47,675
United Kingdom	'	'	'	'	'
SEGMENT AND GEOGRAPHIC INFORMATION	'	'	'	'	'
Revenues:	105,471	77,575	346,166	313,209	'
Revenues, net of interest and transaction-based expenses:	72,764	46,780	235,884	223,506	'
Long-lived Assets, as defined:	11,510	'	11,510	'	10,536
Other	'	'	'	'	'
SEGMENT AND GEOGRAPHIC INFORMATION	'	'	'	'	'
Revenues:	45,895	82,302	149,393	193,413	'
Revenues, net of interest and transaction-based expenses:	43,467	79,816	141,124	185,924	'
Long-lived Assets, as defined:	$4,767	'	$4,767	'	$5,239

SUBSEQUENT_EVENTS_Details

SUBSEQUENT EVENTS (Details) (Subsequent event, Dividend declared, USD $)	Oct. 31, 2013
Subsequent event | Dividend declared	'
SUBSEQUENT EVENTS	'
Cash dividend declared (in dollars per share)	$0.05