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Long-Term Debt - Maturity and Settlement of 1.00% Notes (Details) - USD ($)		12 Months Ended
	Dec. 01, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Shares issued to settle excess over principal for 1.00% Notes	$ 88,700,000	$ 0
Share repurchased value	321,000,000.0	$ 65,400,000	$ 139,000,000.0	$ 315,300,000
Convertible Debt \| 1.00% Notes
Debt Instrument [Line Items]
Debt instrument, interest rate		1.00%
Principal amount of debt	$ 690,000,000.0
Share repurchased value		$ 0
Exercise price, warrants (in dollars per share)		$ 25.96
Convertible Debt \| 1.00% Notes \| Embedded Derivative Financial Instruments
Debt Instrument [Line Items]
Number of convertible shares (in shares)		37,300,000