Acquisitions and Investments	3 Months Ended
Mar. 31, 2018
Business Combinations [Abstract]
Acquisitions and Investments	Acquisitions and Investments On January 2, 2018, we acquired 100% of BondPoint from Virtu Financial, Inc. for $400 million in cash. BondPoint is a leading provider of electronic fixed income trading solutions for the buy-side and sell-side offering access to centralized liquidity and automated trade execution services through its alternative trading system, or ATS, and provides trading services to more than 500 financial services firms. BondPoint is primarily included in our Trading and Clearing segment. The BondPoint purchase price was allocated to the preliminary net tangible and identifiable intangible assets and liabilities based on their estimated fair values as of January 2, 2018. The preliminary identifiable intangible assets acquired were $130 million and included (i) customer relationships of $123 million, which have been assigned a useful life of 15 years, and (ii) developed technology of $7 million, which has been assigned a life of three years. The excess of the purchase price over the preliminary net tangible and identifiable intangible assets was $267 million and was recorded as goodwill. During the three months ended December 31, 2017, we purchased a 4.7% stake in Euroclear valued at €276 million ($327 million), which included our representation on the Euroclear Board of Directors. At the same time, we negotiated an additional purchase which closed on February 21, 2018 following regulatory approval, and which did not include additional representation on the Euroclear Board of Directors. This provided us with an additional 5.1% stake in Euroclear for a purchase price of €246 million in cash ($304 million based on a euro/U.S. dollar exchange rate of 1.2368 as of February 21, 2018), which represents a fair value equivalent to our initial investment. As of March 31, 2018, we owned a 9.8% stake in Euroclear for a total investment of $631 million. Euroclear is a leading provider of post-trade services, including settlement, central securities depositories and related services for cross-border transactions across asset classes. We classify our investment in Euroclear as an equity investment in other non-current assets in the accompanying consolidated balance sheets. As discussed in Note 2, we adopted ASU 2016-01 on January 1, 2018. Under ASU 2016-01, for investments without a readily determinable fair value, we may elect to measure them at cost, less any impairment, plus or minus changes resulting from observable price changes in orderly transactions in similar or identical investments. We have elected to use this approach to estimate the value of the Euroclear investment, as well as our other investments without readily determinable fair values, and it is our policy to apply this treatment to all investments of this nature. An adjustment to estimated fair value is only required for those orderly transactions occurring in similar or identical investments after January 1, 2018, which is the date of adoption, with any adjustment recognized in net income. During the three months ended March 31, 2018, there were no downward or upward adjustments made to the carrying amount of our equity investments for which we have applied the measurement alternative. Pending Acquisition On April 5, 2018, we entered into an agreement to acquire CHX Holdings, or CHX, the parent company of the Chicago Stock Exchange, a full-service stock exchange, including trading, data and corporate listings services. The transaction is expected to close in the second quarter of 2018, subject to regulatory approvals. Subject to SEC approval, CHX will continue to operate as a registered national securities exchange.

Acquisitions and Investments

On January 2, 2018, we acquired 100% of BondPoint from Virtu Financial, Inc. for $400 million in cash. BondPoint is a leading provider of electronic fixed income trading solutions for the buy-side and sell-side offering access to centralized liquidity and automated trade execution services through its alternative trading system, or ATS, and provides trading services to more than 500 financial services firms. BondPoint is primarily included in our Trading and Clearing segment.

The BondPoint purchase price was allocated to the preliminary net tangible and identifiable intangible assets and liabilities based on their estimated fair values as of January 2, 2018. The preliminary identifiable intangible assets acquired were $130 million and included (i) customer relationships of $123 million, which have been assigned a useful life of 15 years, and (ii) developed technology of $7 million, which has been assigned a life of three years. The excess of the purchase price over the preliminary net tangible and identifiable intangible assets was $267 million and was recorded as goodwill.

During the three months ended December 31, 2017, we purchased a 4.7% stake in Euroclear valued at €276 million ($327 million), which included our representation on the Euroclear Board of Directors. At the same time, we negotiated an additional purchase which closed on February 21, 2018 following regulatory approval, and which did not include additional representation on the Euroclear Board of Directors. This provided us with an additional 5.1% stake in Euroclear for a purchase price of €246 million in cash ($304 million based on a euro/U.S. dollar exchange rate of 1.2368 as of February 21, 2018), which represents a fair value equivalent to our initial investment. As of March 31, 2018, we owned a 9.8% stake in Euroclear for a total investment of $631 million. Euroclear is a leading provider of post-trade services, including settlement, central securities depositories and related services for cross-border transactions across asset classes.

We classify our investment in Euroclear as an equity investment in other non-current assets in the accompanying consolidated balance sheets. As discussed in Note 2, we adopted ASU 2016-01 on January 1, 2018. Under ASU 2016-01, for investments without a readily determinable fair value, we may elect to measure them at cost, less any impairment, plus or minus changes resulting from observable price changes in orderly transactions in similar or identical investments. We have elected to use this approach to estimate the value of the Euroclear investment, as well as our other investments without readily determinable fair values, and it is our policy to apply this treatment to all investments of this nature. An adjustment to estimated fair value is only required for those orderly transactions occurring in similar or identical investments after January 1, 2018, which is the date of adoption, with any adjustment recognized in net income. During the three months ended March 31, 2018, there were no downward or upward adjustments made to the carrying amount of our equity investments for which we have applied the measurement alternative.

Pending Acquisition

On April 5, 2018, we entered into an agreement to acquire CHX Holdings, or CHX, the parent company of the Chicago Stock Exchange, a full-service stock exchange, including trading, data and corporate listings services. The transaction is expected to close in the second quarter of 2018, subject to regulatory approvals. Subject to SEC approval, CHX will continue to operate as a registered national securities exchange.