Recent Accounting Pronouncements (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Stockholders' equity	$ 10,160.9	$ 9,879.7	$ 9,491.9	$ 8,571.3	$ 8,351.0	$ 7,738.5
Retained earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' equity	$ 8,349.4	$ 8,168.7	7,818.0	$ 7,000.3	$ 6,771.0	$ 6,247.7
Cumulative Effect, Period Of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' equity			(1.7)
Cumulative Effect, Period Of Adoption, Adjustment | Retained earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' equity			$ (1.7)