Condensed Consolidated Statements of Changes in Stockholders' Equity (unaudited) - USD ($) $ in Millions	Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive loss	Treasury stock
Balance at Dec. 31, 2017	$ 6,863.6	$ 1.0	$ 1,602.9	$ 5,464.6	$ (186.2)	$ (18.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	687.3			687.3
Stock option exercises	53.9	0.1	53.8
Treasury stock sold	4.1		4.0			0.1
Currency translation adjustments	(13.4)				(13.4)
Stock-based compensation	80.2		80.2
Restricted stock activity	(7.3)		(7.3)
Dividends declared	(127.8)			(127.8)
Balance at Sep. 30, 2018	7,554.9	1.1	1,733.6	6,038.4	(199.6)	(18.6)
Balance at Jun. 30, 2018	7,302.9	1.1	1,691.6	5,833.4	(204.6)	(18.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	247.6			247.6
Stock option exercises	14.6		14.6
Treasury stock sold	1.3		1.3
Currency translation adjustments	5.0				5.0
Stock-based compensation	26.8		26.8
Restricted stock activity	(0.7)		(0.7)
Dividends declared	(42.6)			(42.6)
Balance at Sep. 30, 2018	7,554.9	1.1	1,733.6	6,038.4	(199.6)	(18.6)
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)