Consolidated Statements of Shareholders' Equity Statement - USD ($) $ in Millions	Total	Common Stock	Capital in Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock	Non-Controlling Interests
Balance, beginning of period at Dec. 31, 2017	$ 2,857.6	$ 1.2	$ 3,302.6	$ 2,713.0	$ (288.2)	$ (2,953.7)	$ 82.7
Balance, beginning of period (in shares) at Dec. 31, 2017		116,303,729
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	97.0			97.0
Other comprehensive income (loss)	39.4				39.4
Issuances under equity plans	(13.8)		2.9			(16.7)
Issuances under equity plans (in shares)		437,703
Share-based compensation expense	7.5		7.5
Repurchases of common stock	(50.1)					(50.1)
Noncontrolling interest transactions	1.4		0.3				1.1
Balance, end of period at Mar. 31, 2018	2,939.0	$ 1.2	3,313.3	2,825.3	(264.1)	(3,020.5)	83.8
Balance, end of period (in shares) at Mar. 31, 2018		116,741,432
Balance, beginning of period at Dec. 31, 2017	2,857.6	$ 1.2	3,302.6	2,713.0	(288.2)	(2,953.7)	82.7
Balance, beginning of period (in shares) at Dec. 31, 2017		116,303,729
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss)	(89.7)
Balance, end of period at Sep. 30, 2018	2,810.2	$ 1.2	3,326.9	3,060.7	(393.2)	(3,270.1)	84.7
Balance, end of period (in shares) at Sep. 30, 2018		116,787,320
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Unrealized gain reclassified due to new accounting guidance on investments				15.3	(15.3)
Balance, beginning of period at Mar. 31, 2018	2,939.0	$ 1.2	3,313.3	2,825.3	(264.1)	(3,020.5)	83.8
Balance, beginning of period (in shares) at Mar. 31, 2018		116,741,432
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	143.4			143.4
Other comprehensive income (loss)	(111.8)				(111.8)
Issuances under equity plans	(0.6)		(0.1)			(0.5)
Issuances under equity plans (in shares)		36,792
Share-based compensation expense	5.3		5.3
Dividends	(66.0)			(66.0)
Repurchases of common stock	(63.1)					(63.1)
Noncontrolling interest transactions	1.3		1.6				(0.3)
Balance, end of period at Jun. 30, 2018	2,847.5	$ 1.2	3,320.1	2,902.7	(375.9)	(3,084.1)	83.5
Balance, end of period (in shares) at Jun. 30, 2018		116,778,224
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	158.0			158.0
Other comprehensive income (loss)	(17.3)				(17.3)
Issuances under equity plans	0.1		0.1
Issuances under equity plans (in shares)		9,096
Share-based compensation expense	6.7		6.7
Repurchases of common stock	(186.0)					(186.0)
Noncontrolling interest transactions	1.2						1.2
Balance, end of period at Sep. 30, 2018	2,810.2	$ 1.2	3,326.9	3,060.7	(393.2)	(3,270.1)	84.7
Balance, end of period (in shares) at Sep. 30, 2018		116,787,320
Balance, beginning of period at Dec. 31, 2018	2,698.5	$ 1.2	3,337.5	3,157.7	(399.8)	(3,471.7)	73.6
Balance, beginning of period (in shares) at Dec. 31, 2018		116,795,899
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	53.5			53.5
Other comprehensive income (loss)	(2.0)				(2.0)
Issuances under equity plans	(4.9)		0.4			(5.3)
Issuances under equity plans (in shares)		247,325
Share-based compensation expense	4.6		4.6
Repurchases of common stock	(101.0)					(101.0)
Noncontrolling interest transactions	1.2		0.5				0.7
Balance, end of period at Mar. 31, 2019	2,649.9	$ 1.2	3,343.0	3,211.2	(401.8)	(3,578.0)	74.3
Balance, end of period (in shares) at Mar. 31, 2019		117,043,224
Balance, beginning of period at Dec. 31, 2018	2,698.5	$ 1.2	3,337.5	3,157.7	(399.8)	(3,471.7)	73.6
Balance, beginning of period (in shares) at Dec. 31, 2018		116,795,899
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss)	(52.7)
Balance, end of period at Sep. 30, 2019	2,716.1	$ 1.2	3,361.0	3,419.4	(452.5)	(3,631.0)	18.0
Balance, end of period (in shares) at Sep. 30, 2019		117,177,349
Balance, beginning of period at Mar. 31, 2019	2,649.9	$ 1.2	3,343.0	3,211.2	(401.8)	(3,578.0)	74.3
Balance, beginning of period (in shares) at Mar. 31, 2019		117,043,224
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	127.3			127.3
Other comprehensive income (loss)	(14.7)				(14.7)
Issuances under equity plans	2.0		3.9			(1.9)
Issuances under equity plans (in shares)		120,244
Share-based compensation expense	8.3		8.3
Dividends	(65.2)			(65.2)
Noncontrolling interest transactions	(13.1)		(0.8)				(12.3)
Balance, end of period at Jun. 30, 2019	2,694.5	$ 1.2	3,354.4	3,273.3	(416.5)	(3,579.9)	62.0
Balance, end of period (in shares) at Jun. 30, 2019		117,163,468
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	146.1			146.1
Other comprehensive income (loss)	(36.0)				(36.0)
Issuances under equity plans	0.6		0.7			(0.1)
Issuances under equity plans (in shares)		13,881
Share-based compensation expense	5.9		5.9
Repurchases of common stock	(51.0)					(51.0)
Noncontrolling interest transactions	(44.0)						(44.0)
Balance, end of period at Sep. 30, 2019	$ 2,716.1	$ 1.2	$ 3,361.0	$ 3,419.4	$ (452.5)	$ (3,631.0)	$ 18.0
Balance, end of period (in shares) at Sep. 30, 2019		117,177,349