Legal Proceedings	3 Months Ended
Jun. 30, 2012
Legal Proceedings [Abstract]
Legal Proceedings	LEGAL PROCEEDINGS As of June 30, 2012, the end of the period covered by this report, the Company was subject to the various legal proceedings and claims discussed below, as well as certain other legal proceedings and claims that have not been fully resolved and that have arisen in the ordinary course of business. The Company reviews its legal proceedings and claims, regulatory reviews and inspections and other legal proceedings on an ongoing basis and follows appropriate accounting guidance when making accrual and disclosure decisions. The Company establishes accruals for those contingencies where the incurrence of a loss is probable and can be reasonably estimated, and we disclose the amount accrued and the amount of a reasonably possible loss in excess of the amount accrued, if such disclosure is necessary for our financial statements to not be misleading. The Company does not record liabilities when the likelihood that the liability has been incurred is probable, but the amount cannot be reasonably estimated, or when the liability is believed to be only reasonably possible or remote. The Company's assessment of whether a loss is reasonably possible or probable is based on its assessment of the ultimate outcome of the matter following all appeals. Estimates of probable losses resulting from patent litigation involving the Company are inherently difficult to make, particularly when the Company's view of the case is significantly different than that expressed by the plaintiff. The Company has not recorded a liability related to damages in connection with these matters. As of June 30, 2012, the Company does not think that there is a reasonable possibility that any material loss exceeding the amounts already recognized for these reviews, inspections or other legal proceedings, if any, has been incurred. While the consequences of certain unresolved proceedings are not presently determinable, the outcome of any litigation is inherently uncertain and an adverse outcome from certain matters could have a material effect on our earnings in any given reporting period. However, in the opinion of management, the ultimate liability is not expected to have a material effect on our financial position, liquidity or capital resources. Index Options Litigation On May 25, 2012, the Illinois Appellate Court (the "Appellate Court") affirmed the ruling of the Circuit Court of Cook County, Illinois granting CBOE, The McGraw-Hill Companies, Inc and CME Group Index Services, LLC summary judgment against International Securities Exchange ("ISE") and its parent company. The summary judgment motion enjoined ISE from listing or providing an exchange trading market for options on the S&P 500 Index or the Dow Jones Industrial Average and OCC from listing and clearing options on such ISE options. ISE has asked for leave to appeal this decision. Patent Litigation ISE On May 7, 2012, the U.S. Court of Appeals for the Federal Circuit (the “Federal Circuit”) issued a decision on the appeal by ISE of the U.S. District Court in the Northern District of Illinois's (the “District Court”) ruling granting summary judgment to CBOE based on non-infringement of ISE's U.S. Patent No. 6,618,707. In its decision, the Federal Circuit affirmed-in-part and vacated-in-part the ruling of the District Court and remanded the case to the District Court for further proceedings based on the Federal Circuit's construction of terms found in the asserted patent claims. Realtime On August 6, 2012, the Company and Realtime Data, LLC entered into a settlement agreement, the terms of which are confidential, under which the parties agreed to file a stipulation of dismissal of the matter and in connection with which the Company recorded an immaterial charge. Based on the terms of the settlement agreement, the Company has determined that this litigation is not currently a material legal proceeding. Accordingly, the Company does not intend to make disclosures about this proceeding in its future periodic filings.

LEGAL PROCEEDINGS

As of June 30, 2012, the end of the period covered by this report, the Company was subject to the various legal proceedings and claims discussed below, as well as certain other legal proceedings and claims that have not been fully resolved and that have arisen in the ordinary course of business.

The Company reviews its legal proceedings and claims, regulatory reviews and inspections and other legal proceedings on an ongoing basis and follows appropriate accounting guidance when making accrual and disclosure decisions. The Company establishes accruals for those contingencies where the incurrence of a loss is probable and can be reasonably estimated, and we disclose the amount accrued and the amount of a reasonably possible loss in excess of the amount accrued, if such disclosure is necessary for our financial statements to not be misleading. The Company does not record liabilities when the likelihood that the liability has been incurred is probable, but the amount cannot be reasonably estimated, or when the liability is believed to be only reasonably possible or remote. The Company's assessment of whether a loss is reasonably possible or probable is based on its assessment of the ultimate outcome of the matter following all appeals.

Estimates of probable losses resulting from patent litigation involving the Company are inherently difficult to make, particularly when the Company's view of the case is significantly different than that expressed by the plaintiff. The Company has not recorded a liability related to damages in connection with these matters.

As of June 30, 2012, the Company does not think that there is a reasonable possibility that any material loss exceeding the amounts already recognized for these reviews, inspections or other legal proceedings, if any, has been incurred. While the consequences of certain unresolved proceedings are not presently determinable, the outcome of any litigation is inherently uncertain and an adverse outcome from certain matters could have a material effect on our earnings in any given reporting period. However, in the opinion of management, the ultimate liability is not expected to have a material effect on our financial position, liquidity or capital resources.

Index Options Litigation

On May 25, 2012, the Illinois Appellate Court (the "Appellate Court") affirmed the ruling of the Circuit Court of Cook County, Illinois granting CBOE, The McGraw-Hill Companies, Inc and CME Group Index Services, LLC summary judgment against International Securities Exchange ("ISE") and its parent company. The summary judgment motion enjoined ISE from listing or providing an exchange trading market for options on the S&P 500 Index or the Dow Jones Industrial Average and OCC from listing and clearing options on such ISE options. ISE has asked for leave to appeal this decision.

Patent Litigation

ISE

On May 7, 2012, the U.S. Court of Appeals for the Federal Circuit (the “Federal Circuit”) issued a decision on the appeal by ISE of the U.S. District Court in the Northern District of Illinois's (the “District Court”) ruling granting summary judgment to CBOE based on non-infringement of ISE's U.S. Patent No. 6,618,707. In its decision, the Federal Circuit affirmed-in-part and vacated-in-part the ruling of the District Court and remanded the case to the District Court for further proceedings based on the Federal Circuit's construction of terms found in the asserted patent claims.

Realtime

On August 6, 2012, the Company and Realtime Data, LLC entered into a settlement agreement, the terms of which are confidential, under which the parties agreed to file a stipulation of dismissal of the matter and in connection with which the Company recorded an immaterial charge. Based on the terms of the settlement agreement, the Company has determined that this litigation is not currently a material legal proceeding. Accordingly, the Company does not intend to make disclosures about this proceeding in its future periodic filings.