Long-term Debt (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 3,409,700,000		$ 3,418,300,000
Long-term Debt, Fair Value	3,739,900,000		3,995,000,000.0
Long-term Debt, Current Maturities	502,800,000		502,500,000
Long-term Debt, Excluding Current Maturities	2,906,900,000		2,915,800,000
Gain (Loss) on Extinguishment of Debt	(74,000,000.0)	$ 0.0
3.750% Notes Due 2021 (less unamortized discount and issuance costs of $0.1 and $0.5, respectively)
Debt Instrument [Line Items]
Par Value	$ 500,000,000.0
Maturity Date	Oct. 01, 2021
Interest Rate Stated Percentage	3.75%
Effective Interest Rate	3.98%
Unamortized Discount	$ 100,000
Issuance Cost	500,000
Long-term Debt, Gross	499,400,000		499,100,000
4.000% Notes Due 2022
Debt Instrument [Line Items]
Par Value	$ 250,000,000.0
Interest Rate Stated Percentage	4.00%
Effective Interest Rate	4.13%
Long-term Debt, Gross	$ 0		249,300,000
Gain (Loss) on Extinguishment of Debt	9,200,000
3.750% Notes Due 2023
Debt Instrument [Line Items]
Par Value	$ 500,000,000.0
Interest Rate Stated Percentage	3.75%
Effective Interest Rate	4.32%
Long-term Debt, Gross	$ 0		498,800,000
Gain (Loss) on Extinguishment of Debt	36,500,000
4.200% Notes Due 2024 (less unamortized discount and issuance costs of $0.2 and $0.6, respectively)
Debt Instrument [Line Items]
Par Value	$ 500,000,000.0
Effective Interest Rate	4.24%
Long-term Debt, Gross			498,300,000
4.650% Notes Due 2028 (less unamortized discount and issuance costs of $1.3 and $3.4, respectively)
Debt Instrument [Line Items]
Par Value	$ 500,000,000.0
Maturity Date	Oct. 01, 2028
Interest Rate Stated Percentage	4.65%
Effective Interest Rate	4.78%
Unamortized Discount	$ 1,300,000
Issuance Cost	3,400,000
Long-term Debt, Gross	495,300,000		495,200,000
4.750% Notes Due 2030 (less unamortized discount and issuance costs of $3.5 and $5.5, respectively)
Debt Instrument [Line Items]
Par Value	$ 650,000,000.0
Maturity Date	Mar. 30, 2030
Interest Rate Stated Percentage	4.75%
Effective Interest Rate	4.92%
Unamortized Discount	$ 3,500,000
Issuance Cost	5,500,000
Long-term Debt, Gross	641,000,000.0		640,800,000
2.400% Notes Due 2031 (less unamortized discount and issuance costs of $0.8 and $4.7, respectively)
Debt Instrument [Line Items]
Par Value	$ 500,000,000.0
Effective Interest Rate	2.512%
Unamortized Discount	$ 800,000
Issuance Cost	4,700,000
Long-term Debt, Gross	$ 494,500,000		0
3.375% Notes Due 2041 (less unamortized discount and issuance costs of $1.1 and $5.8, respectively)
Debt Instrument [Line Items]
Effective Interest Rate	3.448%
Unamortized Discount	$ 1,100,000
Issuance Cost	5,800,000
Long-term Debt, Gross	493,100,000		0
5.400% Notes Due 2048 (less unamortized discount and issuance costs of $2.7 and $5.1, respectively)
Debt Instrument [Line Items]
Par Value	$ 500,000,000.0
Maturity Date	Oct. 01, 2048
Interest Rate Stated Percentage	5.40%
Effective Interest Rate	5.48%
Unamortized Discount	$ 2,700,000
Issuance Cost	5,100,000
Long-term Debt, Gross	492,200,000		492,100,000
Other notes payable and capitalized leases
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 45,000,000.0		$ 44,700,000
Unsecured Debt 2.400% Note [Member]
Debt Instrument [Line Items]
Interest Rate Stated Percentage	2.40%
Unsecured Debt	$ 494,500,000
Debt Instrument, Unamortized Discount	800,000
Debt Issuance Costs, Gross	4,700,000
Unsecured Debt 3.375% Note
Debt Instrument [Line Items]
Par Value	$ 500,000,000.0
Interest Rate Stated Percentage	3.375%
Unsecured Debt	$ 493,100,000
Debt Instrument, Unamortized Discount	1,100,000
Debt Issuance Costs, Gross	5,800,000
Unsecured Debt 4.200% Notes Remaining Principal
Debt Instrument [Line Items]
Par Value	$ 250,000,000.0
Maturity Date	Apr. 15, 2024
Interest Rate Stated Percentage	4.20%
Unamortized Discount	$ 200,000
Issuance Cost	600,000
Long-term Debt, Gross	249,200,000
Gain (Loss) on Extinguishment of Debt	$ 28,300,000