Long-Term Investments (Details) - USD ($)	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Gain (Loss) on Investments	$ 72,100,000	$ 4,800,000	$ 117,000,000.0
Net cash proceeds from OSTTRA joint venture transaction	0	0	100,700,000
Gain on joint venture	$ 0	$ 0	$ 400,700,000
DME Holdings [Member]
Equity Method Investment, Ownership Percentage	50.00%
Equity Method Investments	$ 13,800,000
OSSTRA
Equity Method Investment, Ownership Percentage	50.00%
Equity Method Investments	$ 1,300,000,000
Net cash proceeds from OSTTRA joint venture transaction	112,500,000
Gain on joint venture	$ 400,700,000
S&P/DJI [Member]
Equity Method Investment, Ownership Percentage	27.00%
Equity Method Investments	$ 1,400,000,000
Payments to Acquire Investments	$ 410,000,000
CFETS
Equity Method Investment, Ownership Percentage	33.00%
Equity Method Investments	$ 51,300,000

Amount of gain (loss) from deconsolidation of subsidiary and derecognition of group of assets constituting transfer of business or nonprofit activity, excluding conveyance of oil and gas mineral rights and transfer of good or service in contract with customer.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Amount of realized and unrealized gain (loss) on investment.

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The cash outflow associated with the purchase of all investments (debt, security, other) during the period.

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The cash inflow associated with the amount received from the sale of a business segment or subsidiary or sale of an entity that is related to it but not strictly controlled during the period (for example, an unconsolidated subsidiary, affiliate, joint venture or equity method investment).

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