Subsequent Events	9 Months Ended
Sep. 30, 2013
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Consent Solicitation and Credit Agreement Amendment On September 30, 2013, the Company commenced a consent solicitation with respect to its outstanding Senior Secured Notes. The Company solicited consents from registered holders (“Holders”) of the Senior Secured Notes to amend, among other things, the terms of the Senior Secured Notes among the Company, The Bank of New York Mellon, as trustee and collateral agent (the “Trustee”), and the guarantors. The amendment was sought to permit the Company to use the funds on deposit in the Collateral Account previously set aside to purchase the Convertible Notes to repay a portion of the principal amount of the borrowings under the Credit Agreement. On October 15, 2013, the Company announced that it had received consents from the Holders of $304.0 million in aggregate principal amount of the Senior Secured Notes, representing 99.68% of the total aggregate principal amount, which met the consent threshold requirement under the Senior Secured Notes Indenture. As a result, the Company entered into the Third Supplemental Indenture with the Trustee to amend the Senior Secured Notes Indenture to permit the purchase, redemption or repayment prior to maturity of the Convertible Notes at any price, including at a premium or at a discount from the face value thereof, with any available cash. In connection with the consent solicitation and the Third Supplemental Indenture, the Company entered into an Amendment to its Credit Agreement with the consent of the requisite percentage of lenders under its First Lien Credit Facility. The Credit Agreement Amendment permits the Company to prepay a portion of the principal amount of borrowings under the First Lien Credit Facility from time to time for a period of 60 days following the effective date of the Credit Agreement Amendment out of the cash set aside in a cash collateral account under the sole dominion and control of the collateral agent under the First Lien Credit Facility for repayments of the Convertible Notes, after which period the remaining cash in that cash collateral account will be required to be used to prepay a portion of the principal amount of borrowings under the First Lien Credit Facility. The Credit Agreement Amendment also permits the purchase, redemption or repayment prior to maturity of the Convertible Notes at any price, including at a premium or at a discount from the face value thereof, with any available cash. See “Principal prepayment under Credit Agreement” for a discussion of the prepayment. In conjunction with the consent solicitation, the Company paid $2.8 million to the Holders and its investment bank. This amount will be included within Other assets on the Consolidated Statements of Financial Condition and will be amortized over the remaining life of the Senior Secured Notes. Principal prepayment under Credit Agreement On October 23, 2013, the Company made a $200.0 million principal prepayment under the Credit Agreement. Under the terms of the Credit Agreement, an amortization payment of $235.0 million is due on July 1, 2014, followed by amortization payments of $7.5 million each quarter beginning September 30, 2014 until maturity on December 5, 2017. The $200.0 million principal prepayment reduces the first $235.0 million amortization payment under the First Lien Credit Facility to $35.0 million. A portion of the $200.0 million was drawn from $117.8 million in cash held in the Collateral Account, which was recorded in Other assets on the Consolidated Statements of Financial Condition at September 30, 2013. As mentioned above, the Company secured the consents necessary from creditors to use the cash in the cash collateral account for the repayment. The remainder of the $200.0 million was paid out of available cash. Settlement with SEC As mentioned in Footnote 17 "Commitments and Contingent Liabilities", on October 16, 2013, KCA reached a settlement with the SEC relating to the August 1, 2012 technology issue. KCA, without admitting or denying the findings, consented to the issuance of an administrative Order relating to controls and procedures required by Section 15(c)(3) of the Securities Exchange Act of 1934 and SEC Rule 15c3-5 (the “Market Access Rule”), and Rules 200(g) and 203(b) of Regulation SHO (the “Short Sale Rules”). Under the terms of the settlement, KCA was censured, paid a civil penalty in the sum of $12.0 million and is required to cease and desist from committing future violations of the Market Access Rule and the Short Sale Rules. KCA must also retain an independent consultant to conduct a comprehensive review of KCA’s compliance with the Market Access Rule. The settlement resolves the SEC’s investigation relating to the August 1, 2012 technology issue. The full amount of this settlement had been accrued on Knight's July 1, 2013 balance sheet acquired by the Company and included in Accrued expenses and other liabilities on the September 30, 2013 Consolidated Statements of Financial Condition. The foregoing description of the settlement is qualified in its entirety by the full text of the SEC’s Order which is incorporated by reference herein to Exhibit 10.1 of the Current Report on Form 8-K filed by the Company on October 16, 2013. Reduction in force On October 22, 2013, in connection with post-closing merger integration and rationalization of redundancies across the combined firms, the Company commenced a workforce reduction plan. The workforce reduction plan impacted approximately 5% of the Company’s global workforce, all of whom have been notified. The Company currently estimates that it will recognize a pre-tax charge in connection with the workforce reduction of approximately $9.4 million during the fourth quarter of 2013. The charge is expected to consist of severance, other one-time termination benefits, and other associated costs.

Subsequent Events

Consent Solicitation and Credit Agreement Amendment

On September 30, 2013, the Company commenced a consent solicitation with respect to its outstanding Senior Secured Notes. The Company solicited consents from registered holders (“Holders”) of the Senior Secured Notes to amend, among other things, the terms of the Senior Secured Notes among the Company, The Bank of New York Mellon, as trustee and collateral agent (the “Trustee”), and the guarantors. The amendment was sought to permit the Company to use the funds on deposit in the Collateral Account previously set aside to purchase the Convertible Notes to repay a portion of the principal amount of the borrowings under the Credit Agreement.

On October 15, 2013, the Company announced that it had received consents from the Holders of $304.0 million in aggregate principal amount of the Senior Secured Notes, representing 99.68% of the total aggregate principal amount, which met the consent threshold requirement under the Senior Secured Notes Indenture.

As a result, the Company entered into the Third Supplemental Indenture with the Trustee to amend the Senior Secured Notes Indenture to permit the purchase, redemption or repayment prior to maturity of the Convertible Notes at any price, including at a premium or at a discount from the face value thereof, with any available cash.

In connection with the consent solicitation and the Third Supplemental Indenture, the Company entered into an Amendment to its Credit Agreement with the consent of the requisite percentage of lenders under its First Lien Credit Facility. The Credit Agreement Amendment permits the Company to prepay a portion of the principal amount of borrowings under the First Lien Credit Facility from time to time for a period of 60 days following the effective date of the Credit Agreement Amendment out of the cash set aside in a cash collateral account under the sole dominion and control of the collateral agent under the First Lien Credit Facility for repayments of the Convertible Notes, after which period the remaining cash in that cash collateral account will be required to be used to prepay a portion of the principal amount of borrowings under the First Lien Credit Facility. The Credit Agreement Amendment also permits the purchase, redemption or repayment prior to maturity of the Convertible Notes at any price, including at a premium or at a discount from the face value thereof, with any available cash. See “Principal prepayment under Credit Agreement” for a discussion of the prepayment.

In conjunction with the consent solicitation, the Company paid $2.8 million to the Holders and its investment bank. This amount will be included within Other assets on the Consolidated Statements of Financial Condition and will be amortized over the remaining life of the Senior Secured Notes.

Principal prepayment under Credit Agreement

On October 23, 2013, the Company made a $200.0 million principal prepayment under the Credit Agreement. Under the terms of the Credit Agreement, an amortization payment of $235.0 million is due on July 1, 2014, followed by amortization payments of $7.5 million each quarter beginning September 30, 2014 until maturity on December 5, 2017. The $200.0 million principal prepayment reduces the first $235.0 million amortization payment under the First Lien Credit Facility to $35.0 million.

A portion of the $200.0 million was drawn from $117.8 million in cash held in the Collateral Account, which was recorded in Other assets on the Consolidated Statements of Financial Condition at September 30, 2013. As mentioned above, the Company secured the consents necessary from creditors to use the cash in the cash collateral account for the repayment. The remainder of the $200.0 million was paid out of available cash.

Settlement with SEC

As mentioned in Footnote 17 "Commitments and Contingent Liabilities", on October 16, 2013, KCA reached a settlement with the SEC relating to the August 1, 2012 technology issue.

KCA, without admitting or denying the findings, consented to the issuance of an administrative Order relating to controls and procedures required by Section 15(c)(3) of the Securities Exchange Act of 1934 and SEC Rule 15c3-5 (the “Market Access Rule”), and Rules 200(g) and 203(b) of Regulation SHO (the “Short Sale Rules”). Under the terms of the settlement, KCA was censured, paid a civil penalty in the sum of $12.0 million and is required to cease and desist from committing future violations of the Market Access Rule and the Short Sale Rules. KCA must also retain an independent consultant to conduct a comprehensive review of KCA’s compliance with the Market Access Rule. The settlement resolves the SEC’s investigation relating to the August 1, 2012 technology issue. The full amount of this settlement had been accrued on Knight's July 1, 2013 balance sheet acquired by the Company and included in Accrued expenses and other liabilities on the September 30, 2013 Consolidated Statements of Financial Condition. The foregoing description of the settlement is qualified in its entirety by the full text of the SEC’s Order which is incorporated by reference herein to Exhibit 10.1 of the Current Report on Form 8-K filed by the Company on October 16, 2013.

Reduction in force

On October 22, 2013, in connection with post-closing merger integration and rationalization of redundancies across the combined firms, the Company commenced a workforce reduction plan. The workforce reduction plan impacted approximately 5% of the Company’s global workforce, all of whom have been notified. The Company currently estimates that it will recognize a pre-tax charge in connection with the workforce reduction of approximately $9.4 million during the fourth quarter of 2013. The charge is expected to consist of severance, other one-time termination benefits, and other associated costs.