Credit Agreement	12 Months Ended
Dec. 31, 2020
Debt Disclosure [Abstract]
Credit Agreement	13. Credit Agreements Revolving Credit Agreement In October 2015, the Company entered into a two-year amended and restated credit agreement (the “Prior Credit Agreement”) that provided for revolving loans and letters of credit up to an aggregate of $100.0 million. The maturity date of the Prior Credit Agreement was subsequently extended to November 2020. On August 19, 2020, the Company amended the Prior Credit Agreement to, among other things, (i) permit investments of up to $500 million in MarketAxess Corporation and (ii) increase the aggregate commitments of the lender under the Credit Agreement from $100 million to $450 million. The Prior Credit Agreement matured on November 13, 2020, when the Company entered into a new one-year credit agreement. Borrowings under the Prior Credit Agreement bore interest at a rate per annum equal to the base rate or adjusted LIBOR plus an applicable margin that varied with the Company’s consolidated total leverage ratio. In November 2020, the Company entered into a credit agreement (the “Credit Agreement”) with a syndicate of lenders and JPMorgan Chase Bank, N.A., as administrative agent, that provides aggregate commitments totaling $500 million, consisting of a revolving credit facility and a $5 million letter of credit sub-limit for standby letters of credit. The Credit Agreement replaced the Prior Credit Agreement and will mature on November 12, 2021, with the Company’s option to request up to two additional 364-day extensions at the discretion of each lender and subject to customary conditions. Subject to satisfaction of certain specified conditions, the Company is permitted to upsize the Credit Agreement by up to $250 million in total. As of December 31, 2020, the Company had $1.0 million in letters of credit outstanding and $499.0 million in available borrowing capacity under the Credit Agreement. Borrowings under the Credit Agreement will bear interest at a rate per annum equal to the base rate or adjusted LIBOR plus an applicable margin that varies with the Company’s consolidated total leverage ratio. The Credit Agreement requires that the Company satisfy certain covenants, which include leverage ratios and minimum earnings before interest, tax, and depreciation and amortization (“EBITDA”) requirements. The Company was in compliance with all applicable covenants at December 31, 2020. The Company incurred an aggregate of $0.8 million of interest expense on borrowings under the Credit Agreement and the Prior Credit Agreement for the year ended December 31, 2020. Collateralized Agreement In connection with its self-clearing operations, one of the Company’s broker-dealer subsidiaries entered into an agreement (the “Collateralized Agreement”) with its settlement bank to provide loans to the subsidiary in amounts up to an aggregate of $200.0 million on an uncommitted basis. Borrowings under the Collateralized Agreement are collateralized by securities pledged by the Company’s broker-dealer subsidiary to the settlement bank, subject to applicable haircuts and concentration limits. Borrowings under the Collateralized Agreement will bear interest at a rate per annum equal to the Federal Funds Rate plus 1.00%. The Company incurred $0.1 million of interest expense on borrowings under the Collateralized Agreement during the year ended December 31, 2020. As of December 31, 2020, the Company had no borrowings outstanding and $200.0 million in available borrowing capacity under the Collateralized Agreement.

Credit Agreement

12 Months Ended

Dec. 31, 2020

13. Credit Agreements

Revolving Credit Agreement

In October 2015, the Company entered into a two-year amended and restated credit agreement (the “Prior Credit Agreement”) that provided for revolving loans and letters of credit up to an aggregate of $100.0 million. The maturity date of the Prior Credit Agreement was subsequently extended to November 2020. On August 19, 2020, the Company amended the Prior Credit Agreement to, among other things, (i) permit investments of up to $500 million in MarketAxess Corporation and (ii) increase the aggregate commitments of the lender under the Credit Agreement from $100 million to $450 million. The Prior Credit Agreement matured on November 13, 2020, when the Company entered into a new one-year credit agreement. Borrowings under the Prior Credit Agreement bore interest at a rate per annum equal to the base rate or adjusted LIBOR plus an applicable margin that varied with the Company’s consolidated total leverage ratio.

In November 2020, the Company entered into a credit agreement (the “Credit Agreement”) with a syndicate of lenders and JPMorgan Chase Bank, N.A., as administrative agent, that provides aggregate commitments totaling $500 million, consisting of a revolving credit facility and a $5 million letter of credit sub-limit for standby letters of credit. The Credit Agreement replaced the Prior Credit Agreement and will mature on November 12, 2021, with the Company’s option to request up to two additional 364-day extensions at the discretion of each lender and subject to customary conditions. Subject to satisfaction of certain specified conditions, the Company is permitted to upsize the Credit Agreement by up to $250 million in total. As of December 31, 2020, the Company had $1.0 million in letters of credit outstanding and $499.0 million in available borrowing capacity under the Credit Agreement.

Borrowings under the Credit Agreement will bear interest at a rate per annum equal to the base rate or adjusted LIBOR plus an applicable margin that varies with the Company’s consolidated total leverage ratio. The Credit Agreement requires that the Company satisfy certain covenants, which include leverage ratios and minimum earnings before interest, tax, and depreciation and amortization (“EBITDA”) requirements. The Company was in compliance with all applicable covenants at December 31, 2020. The Company incurred an aggregate of $0.8 million of interest expense on borrowings under the Credit Agreement and the Prior Credit Agreement for the year ended December 31, 2020.

Collateralized Agreement

In connection with its self-clearing operations, one of the Company’s broker-dealer subsidiaries entered into an agreement (the “Collateralized Agreement”) with its settlement bank to provide loans to the subsidiary in amounts up to an aggregate of $200.0 million on an uncommitted basis. Borrowings under the Collateralized Agreement are collateralized by securities pledged by the Company’s broker-dealer subsidiary to the settlement bank, subject to applicable haircuts and concentration limits. Borrowings under the Collateralized Agreement will bear interest at a rate per annum equal to the Federal Funds Rate plus 1.00%. The Company incurred $0.1 million of interest expense on borrowings under the Collateralized Agreement during the year ended December 31, 2020. As of December 31, 2020, the Company had no borrowings outstanding and $200.0 million in available borrowing capacity under the Collateralized Agreement.