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Share Repurchases (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended			56 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	May 14, 2015
Equity, Class of Treasury Stock [Line Items]
Accrued liabilities	$ 1,233.1	$ 1,081.9		$ 1,081.9
Payments for Repurchase of Common Stock	$ 0.0	$ 149.9	$ 0.0
2015 Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Authorized Amount					$ 1,500.0
Stock Repurchased and Retired During Period, Shares	0.0			22.9
Payments for Repurchase of Common Stock				$ 800.0
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 700.0