Concentrations of Credit Risk	9 Months Ended
Sep. 30, 2021
Risks and Uncertainties [Abstract]
Concentrations of Credit Risk	Concentrations of Credit RiskFinancial instruments could potentially expose us to concentrations of credit risk, including unsecured receivables from the Exchange. A large majority of our revenue and receivables are from the Exchange and its affiliates. See also Note 1, "Nature of Operations". Net management fee amounts and other reimbursements due from the Exchange and its affiliates were $503.4 million and $494.6 million at September 30, 2021 and December 31, 2020, respectively, which includes a current expected credit loss allowance of $0.6 million in both periods.

The entire disclosure for any concentrations existing at the date of the financial statements that make an entity vulnerable to a reasonably possible, near-term, severe impact. This disclosure informs financial statement users about the general nature of the risk associated with the concentration, and may indicate the percentage of concentration risk as of the balance sheet date.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-URI http://asc.fasb.org/topic&trid=2134479

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