The amount of reduction in net assets resulting from deconsolidation.

No definition available.

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- Definition

The percentage of equity investment securities.

+ References

No definition available.

+ Details

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- Definition

The carrying amount as on the balance sheet date of interest bearing notes receivables.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the percentage of voting interest held by the company.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
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- Definition

Amount of dividend reversed during the period subsequent to declaration.

+ References

No definition available.

+ Details

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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=99377092&loc=SL75136599-209740

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of the reduction or elimination during the period of a noncontrolling interest resulting from the parent's loss of control and deconsolidation of the entity in which one or more outside parties had a noncontrolling interest.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=109239629&loc=SL4573702-111684

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

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Balance Type:
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- Details

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Balance Type:
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- Details

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INVESTMENTS - Other Equity Investments (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Aug. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Other Equity Investments
Other Equity Investments		$ 39.0		$ 38.3
Investment in OCC
Other Equity Investments
Other Equity Investments		$ 0.3		0.3
Percentage of equity securities		20.00%
Investment in OCC \| Other expense
Other Equity Investments
Dividend reversed			$ 8.8
Investment in Cboe Vest Financial Group, Inc.
Other Equity Investments
Other Equity Investments	$ 2.9	$ 2.9		$ 2.9
Decrease in net assets due to deconsolidation	14.5
Noncontrolling Interest, Decrease from Deconsolidation	5.8
Interest bearing notes receivable	$ 3.7
Investment in Cboe Vest Financial Group, Inc. \| Maximum
Other Equity Investments
Ownership percentage	20.00%
Percentage of voting interest	5.00%