Debt - Short-Term and Long-Term Debt (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Mar. 06, 2019	Jan. 15, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Finance lease liabilities, current	$ 14.9
Finance lease liabilities, current				$ 7.8
Short-term debt and current portion of long-term debt	24.9			672.8
Finance lease liabilities, noncurrent	20.8
Finance lease liabilities, noncurrent				19.5
Syndicated revolving credit facility debt issuance costs	(2.1)			(2.9)
Long-term debt	2,668.4			2,050.5
Total debt	$ 2,693.3			2,723.3
4.875% Senior Note
Debt Instrument [Line Items]
Debt issuance date	Dec. 08, 2011
Debt maturity date	Jan. 15, 2019
Short-term debt	$ 0.0			250.0
Long term debt instrument interest rate stated percentage	4.875%		4.875%
4.125% Senior Note
Debt Instrument [Line Items]
Debt issuance date	Mar. 06, 2019
Debt maturity date	Mar. 15, 2029
Long-term debt	$ 613.9			0.0
Long term debt instrument interest rate stated percentage	4.125%	4.125%
Unamortized discount on senior notes	$ 13.9	$ (2.1)
4.000% Senior Note
Debt Instrument [Line Items]
Debt issuance date	May 15, 2015
Debt maturity date	Jun. 15, 2025
Long-term debt	$ 893.0			892.1
Long term debt instrument interest rate stated percentage	4.00%
Unamortized discount on senior notes	$ (7.0)			(7.9)
5.500% Senior Note
Debt Instrument [Line Items]
Debt issuance date	May 15, 2015
Debt maturity date	Jun. 15, 2045
Long-term debt	$ 345.4			345.3
Long term debt instrument interest rate stated percentage	5.50%
Unamortized discount on senior notes	$ (4.6)			(4.7)
4.125% Senior Note
Debt Instrument [Line Items]
Debt issuance date	Sep. 12, 2012
Debt maturity date	Sep. 12, 2022
Long-term debt	$ 348.2			347.7
Long term debt instrument interest rate stated percentage	4.125%
Unamortized discount on senior notes	$ (1.8)			(2.3)
5.800% Senior Note
Debt Instrument [Line Items]
Debt issuance date	Apr. 06, 2011
Debt maturity date	May 01, 2021
Long-term debt	$ 449.2			448.8
Long term debt instrument interest rate stated percentage	5.80%
Unamortized discount on senior notes	$ (0.8)			(1.2)
Line of Credit
Debt Instrument [Line Items]
Syndicated revolving credit facility	$ 10.0			$ 415.0