Investments - Equity Securities without Readily Determinable Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Investments, All Other Investments [Abstract]
Initial cost	$ 86.0	$ 74.4
Cumulative upward adjustments	58.6	42.7
Cumulative downward adjustments (including impairments)	(15.4)	(15.4)
Carrying value	$ 129.2	$ 101.7

Equity Securities without Readily Determinable Fair Value, Initial Cost

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- Definition

Amount of investment in equity security without readily determinable fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126980263&loc=SL75117539-209714

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- Definition

Amount of cumulative loss from downward price adjustment on investment in equity security without readily determinable fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126980263&loc=SL75117539-209714

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- Definition

Amount of cumulative gain from upward price adjustment on investment in equity security without readily determinable fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=126980263&loc=SL75117539-209714

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- References

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