Fair Value Measurements - Carrying Amounts and Estimated Fair Values by Input Level (Details) - USD ($) $ in Millions	Sep. 30, 2021	Jul. 01, 2021	Dec. 31, 2020	May 31, 2020	Jan. 19, 2017
Financial assets:
Equity securities	$ 176.8		$ 143.1
Senior Notes | 5.625% Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate	5.625%		5.625%		5.625%
Senior Notes | 4.125% Notes due 2029
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate	4.125%	4.125%
Convertible Notes | 2.75% Convertible Notes due 2026
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate	2.75%			2.75%
Recurring | Level 1
Financial assets:
Cash and cash equivalents	$ 2,729.3		$ 1,853.8
Equity securities	0.0		0.0
Held-to-maturity securities	0.0		0.0
Promissory notes	0.0		0.0
Puts and calls related to certain Barstool Sports shares	0.0
Financial liabilities:
Other liabilities	0.0		0.0
Puts and calls related to certain Barstool Sports shares			0.0
Recurring | Level 1 | Senior Secured Credit Facilities
Financial liabilities:
Long-term debt	1,575.6		1,609.3
Recurring | Level 1 | Senior Notes | 5.625% Notes
Financial liabilities:
Long-term debt	413.5		418.0
Recurring | Level 1 | Senior Notes | 4.125% Notes due 2029
Financial liabilities:
Long-term debt	393.5
Recurring | Level 1 | Convertible Notes | 2.75% Convertible Notes due 2026
Financial liabilities:
Long-term debt	1,058.8		1,274.5
Recurring | Level 1 | Other long-term obligations
Financial liabilities:
Long-term debt	0.0		0.0
Recurring | Level 2
Financial assets:
Cash and cash equivalents	0.0		0.0
Equity securities	176.8		143.1
Held-to-maturity securities	6.7		6.7
Promissory notes	15.1		15.1
Puts and calls related to certain Barstool Sports shares	1.5
Financial liabilities:
Other liabilities	2.8		2.8
Puts and calls related to certain Barstool Sports shares			0.3
Recurring | Level 2 | Senior Secured Credit Facilities
Financial liabilities:
Long-term debt	0.0		0.0
Recurring | Level 2 | Senior Notes | 5.625% Notes
Financial liabilities:
Long-term debt	0.0		0.0
Recurring | Level 2 | Senior Notes | 4.125% Notes due 2029
Financial liabilities:
Long-term debt	0.0
Recurring | Level 2 | Convertible Notes | 2.75% Convertible Notes due 2026
Financial liabilities:
Long-term debt	0.0		0.0
Recurring | Level 2 | Other long-term obligations
Financial liabilities:
Long-term debt	62.0		72.8
Recurring | Level 3
Financial assets:
Cash and cash equivalents	0.0		0.0
Equity securities	0.0		0.0
Held-to-maturity securities	0.0		0.0
Promissory notes	0.0		0.0
Puts and calls related to certain Barstool Sports shares	0.0
Financial liabilities:
Other liabilities	10.5		7.3
Puts and calls related to certain Barstool Sports shares			0.0
Recurring | Level 3 | Senior Secured Credit Facilities
Financial liabilities:
Long-term debt	0.0		0.0
Recurring | Level 3 | Senior Notes | 5.625% Notes
Financial liabilities:
Long-term debt	0.0		0.0
Recurring | Level 3 | Senior Notes | 4.125% Notes due 2029
Financial liabilities:
Long-term debt	0.0
Recurring | Level 3 | Convertible Notes | 2.75% Convertible Notes due 2026
Financial liabilities:
Long-term debt	0.0		0.0
Recurring | Level 3 | Other long-term obligations
Financial liabilities:
Long-term debt	84.6		0.0
Recurring | Carrying Amount
Financial assets:
Cash and cash equivalents	2,729.3		1,853.8
Equity securities	176.8		143.1
Held-to-maturity securities	6.7		6.7
Promissory notes	15.1		15.1
Puts and calls related to certain Barstool Sports shares	1.5
Financial liabilities:
Other liabilities	13.3		10.1
Puts and calls related to certain Barstool Sports shares			0.3
Recurring | Carrying Amount | Senior Secured Credit Facilities
Financial liabilities:
Long-term debt	1,558.5		1,600.3
Recurring | Carrying Amount | Senior Notes | 5.625% Notes
Financial liabilities:
Long-term debt	399.6		399.5
Recurring | Carrying Amount | Senior Notes | 4.125% Notes due 2029
Financial liabilities:
Long-term debt	392.7
Recurring | Carrying Amount | Convertible Notes | 2.75% Convertible Notes due 2026
Financial liabilities:
Long-term debt	250.0		239.8
Recurring | Carrying Amount | Other long-term obligations
Financial liabilities:
Long-term debt	148.7		73.0
Recurring | Fair Value
Financial assets:
Cash and cash equivalents	2,729.3		1,853.8
Equity securities	176.8		143.1
Held-to-maturity securities	6.7		6.7
Promissory notes	15.1		15.1
Puts and calls related to certain Barstool Sports shares	1.5
Financial liabilities:
Other liabilities	13.3		10.1
Puts and calls related to certain Barstool Sports shares			0.3
Recurring | Fair Value | Senior Secured Credit Facilities
Financial liabilities:
Long-term debt	1,575.6		1,609.3
Recurring | Fair Value | Senior Notes | 5.625% Notes
Financial liabilities:
Long-term debt	413.5		418.0
Recurring | Fair Value | Senior Notes | 4.125% Notes due 2029
Financial liabilities:
Long-term debt	393.5
Recurring | Fair Value | Convertible Notes | 2.75% Convertible Notes due 2026
Financial liabilities:
Long-term debt	1,058.8		1,274.5
Recurring | Fair Value | Other long-term obligations
Financial liabilities:
Long-term debt	$ 146.6		$ 72.8