Condensed Consolidated Statements of Changes in Stockholders' Equity (unaudited) - USD ($) $ in Millions	Total	Cumulative Effect, Period Of Adoption, Adjustment	Common stock	Additional paid-in capital	Retained earnings	Retained earnings Cumulative Effect, Period Of Adoption, Adjustment	Accumulated other comprehensive loss	Treasury stock
Balance at Dec. 31, 2018	$ 7,738.5		$ 1.1	$ 1,751.5	$ 6,247.7		$ (243.3)	$ (18.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	896.8				896.8
Stock option exercises	55.8			55.8
Treasury stock sold	5.2			5.0				0.2
Currency translation adjustments	(41.8)						(41.8)
Stock-based compensation	77.9			77.9
Restricted stock activity	(16.9)			(16.9)
Dividends declared	(144.2)				(144.2)
Balance at Sep. 30, 2019	8,571.3		1.1	1,873.3	7,000.3		(285.1)	(18.3)
Balance at Jun. 30, 2019	8,351.0		1.1	1,840.5	6,771.0		(243.2)	(18.4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	277.5				277.5
Stock option exercises	6.7			6.7
Treasury stock sold	1.6			1.5				0.1
Currency translation adjustments	(41.9)						(41.9)
Stock-based compensation	25.4			25.4
Restricted stock activity	(0.8)			(0.8)
Dividends declared	(48.2)				(48.2)
Balance at Sep. 30, 2019	8,571.3		1.1	1,873.3	7,000.3		(285.1)	(18.3)
Balance at Dec. 31, 2019	9,491.9	$ (1.7)	1.1	1,903.9	7,818.0	$ (1.7)	(212.8)	(18.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	693.9				693.9
Stock option exercises	88.9			88.9
Treasury stock sold	7.3			7.1				0.2
Currency translation adjustments	(28.6)						(28.6)
Stock-based compensation	86.4			86.4
Restricted stock activity	(16.4)			(16.4)
Dividends declared	(160.8)				(160.8)
Balance at Sep. 30, 2020	$ 10,160.9		1.1	2,069.9	8,349.4		(241.4)	(18.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Balance at Jun. 30, 2020	$ 9,879.7		1.1	2,012.9	8,168.7		(284.8)	(18.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	234.4				234.4
Stock option exercises	25.9			25.9
Treasury stock sold	2.8			2.7				0.1
Currency translation adjustments	43.4						43.4
Stock-based compensation	29.5			29.5
Restricted stock activity	(1.1)			(1.1)
Dividends declared	(53.7)				(53.7)
Balance at Sep. 30, 2020	$ 10,160.9		$ 1.1	$ 2,069.9	$ 8,349.4		$ (241.4)	$ (18.1)