Fair Value Measurements - Carrying Amounts and Estimated Fair Values by Input Level (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020	Jan. 19, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate	5.625%
Financial assets:
Equity securities	$ 161.9	$ 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%
Recurring | Level 1
Financial assets:
Cash and cash equivalents	$ 2,274.7	$ 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	1,588.7	1,609.3
Recurring | Level 1 | Senior Notes | 5.625% Notes
Financial liabilities:
Long-term debt	415.0	418.0
Recurring | Level 1 | Senior Notes | 2.75% Convertible Notes due 2026
Financial liabilities:
Long-term debt	1,093.9	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	161.9	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	2.8
Financial liabilities:
Other liabilities	2.6	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 | 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	11.6	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 | 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	77.7	0.0
Recurring | Carrying Amount
Financial assets:
Cash and cash equivalents	2,274.7	1,853.8
Equity securities	161.9	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	2.8
Financial liabilities:
Other liabilities	14.4	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	1,572.4	1,600.3
Recurring | Carrying Amount | Senior Notes | 5.625% Notes
Financial liabilities:
Long-term debt	399.5	399.5
Recurring | Carrying Amount | Senior Notes | 2.75% Convertible Notes due 2026
Financial liabilities:
Long-term debt	246.5	239.8
Recurring | Carrying Amount | Other long-term obligations
Financial liabilities:
Long-term debt	141.9	73.0
Recurring | Fair Value
Financial assets:
Cash and cash equivalents	2,274.7	1,853.8
Equity securities	161.9	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	2.8
Financial liabilities:
Other liabilities	14.2	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	1,588.7	1,609.3
Recurring | Fair Value | Senior Notes | 5.625% Notes
Financial liabilities:
Long-term debt	415.0	418.0
Recurring | Fair Value | Senior Notes | 2.75% Convertible Notes due 2026
Financial liabilities:
Long-term debt	1,093.9	1,274.5
Recurring | Fair Value | Other long-term obligations
Financial liabilities:
Long-term debt	$ 139.7	$ 72.8