Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Paid-In Capital	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive Loss	Noncontrolling Interests	Total
Balance (in shares) at Dec. 31, 2018		185.7
Balance at Dec. 31, 2018		$ 1.9	$ 1,947.3	$ (139.9)	$ 363.1	$ (282.7)	$ 92.5	$ 1,982.2
Net Income (Loss) Attributable to Parent					70.9
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest							2.4
Net income (loss)								73.4
Other comprehensive income						53.2	0.1	53.3
Stock-based compensation			9.2					9.2
Employee share purchase plan		0.1
Employee share purchase plan		$ 0.0	6.9					6.9
Exercise of stock options		0.5
Exercise of stock options		$ 0.0	4.2					4.2
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures		$ 0.0
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures		1.6
Treasury stock purchased		(0.6)
Treasury stock purchased				(37.1)				(37.1)
Dividends to shareholders					(14.2)			(14.2)
Balance (in shares) at Mar. 31, 2019		187.3
Balance at Mar. 31, 2019		$ 1.9	1,967.6	(177.0)	418.8	(229.4)	95.0	2,076.9
Balance (in shares) at Dec. 31, 2018		185.7
Balance at Dec. 31, 2018		$ 1.9	1,947.3	(139.9)	363.1	(282.7)	92.5	1,982.2
Net Income (Loss) Attributable to Parent	$ 264.1
Net income (loss)	265.6
Other comprehensive income	(87.7)
Balance (in shares) at Sep. 30, 2019		188.3
Balance at Sep. 30, 2019		$ 1.9	1,999.7	(177.9)	583.4	(369.7)	92.1	2,129.5
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets | Accounting Standards Update 2017-12 [Member]					(1.0)			(1.0)
Balance (in shares) at Mar. 31, 2019		187.3
Balance at Mar. 31, 2019		$ 1.9	1,967.6	(177.0)	418.8	(229.4)	95.0	2,076.9
Net Income (Loss) Attributable to Parent					101.5
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest							2.5
Net income (loss)								104.0
Other comprehensive income						(66.8)	0.7	(66.1)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders							(0.8)	(0.8)
Stock-based compensation			6.1					6.1
Exercise of stock options		0.5
Exercise of stock options		$ 0.0	2.7					2.7
Treasury stock purchased		0.0
Treasury stock purchased				(0.1)				(0.1)
Dividends to shareholders					(14.2)			(14.2)
Balance (in shares) at Jun. 30, 2019		187.8
Balance at Jun. 30, 2019		$ 1.9	1,976.4	(177.1)	506.1	(296.2)	97.4	2,108.5
Net Income (Loss) Attributable to Parent	91.7				91.7
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest							(3.4)
Net income (loss)	88.3							88.3
Other comprehensive income	(74.9)					(73.5)	(1.4)	(74.9)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders							(0.5)	(0.5)
Stock-based compensation			12.4					12.4
Employee share purchase plan		0.1
Employee share purchase plan		$ 0.0	8.3					8.3
Exercise of stock options		0.4
Exercise of stock options		$ 0.0	2.6					2.6
Treasury stock purchased		0.0
Treasury stock purchased				(0.8)				(0.8)
Dividends to shareholders					(14.3)			(14.3)
Stockholders' Equity, Other					0.1			0.1
Balance (in shares) at Sep. 30, 2019		188.3
Balance at Sep. 30, 2019		$ 1.9	1,999.7	(177.9)	583.4	(369.7)	92.1	2,129.5
Balance (in shares) at Dec. 31, 2019		188.7
Balance at Dec. 31, 2019	2,339.4	$ 1.9	2,022.3	(179.2)	652.0	(251.6)	94.0	2,339.4
Net Income (Loss) Attributable to Parent					70.2
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest							4.1
Net income (loss)								74.3
Other comprehensive income						(216.6)	(1.7)	(218.3)
Stock-based compensation			4.1					4.1
Employee share purchase plan		0.1
Employee share purchase plan		$ 0.0	8.9					8.9
Exercise of stock options		0.4
Exercise of stock options		$ 0.0	2.8					2.8
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures		$ 0.0
Vesting of restricted stock units		0.9
Treasury stock purchased		(0.3)
Treasury stock purchased				(32.6)				(32.6)
Dividends to shareholders					(14.4)			(14.4)
Stockholders' Equity, Other					(0.1)		0.1	0.0
Balance (in shares) at Mar. 31, 2020		189.8
Balance at Mar. 31, 2020		$ 1.9	2,038.1	(211.8)	707.7	(468.2)	96.5	2,164.2
Balance (in shares) at Dec. 31, 2019		188.7
Balance at Dec. 31, 2019	2,339.4	$ 1.9	2,022.3	(179.2)	652.0	(251.6)	94.0	2,339.4
Net Income (Loss) Attributable to Parent	241.5
Net income (loss)	251.0
Other comprehensive income	(159.5)
Balance (in shares) at Sep. 30, 2020		190.3
Balance at Sep. 30, 2020	2,402.2	$ 2.0	2,074.0	(214.7)	850.3	(409.7)	100.3	2,402.2
Balance (in shares) at Mar. 31, 2020		189.8
Balance at Mar. 31, 2020		$ 1.9	2,038.1	(211.8)	707.7	(468.2)	96.5	2,164.2
Net Income (Loss) Attributable to Parent					68.5
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest							1.5
Net income (loss)								70.0
Other comprehensive income						(0.4)	(0.2)	(0.6)
Stock-based compensation			15.9					15.9
Exercise of stock options		0.3
Exercise of stock options		$ 0.1	2.5					2.6
Treasury stock purchased		0.0
Treasury stock purchased				(0.4)				(0.4)
Dividends to shareholders					(14.5)			(14.5)
Stockholders' Equity, Other			(0.1)				(0.5)	(0.6)
Balance (in shares) at Jun. 30, 2020		190.1
Balance at Jun. 30, 2020		$ 2.0	2,056.4	(212.2)	761.7	(468.6)	97.3	2,236.6
Net Income (Loss) Attributable to Parent	102.8				102.8
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest							3.9
Net income (loss)	106.7							106.7
Other comprehensive income	59.5					58.9	0.6	59.5
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders							(1.4)	(1.4)
Stock-based compensation			7.2					7.2
Employee share purchase plan		0.1
Employee share purchase plan		$ 0.0	10.2					10.2
Exercise of stock options		0.0
Exercise of stock options		$ 0.0	0.2					0.2
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures		$ 0.0
Vesting of restricted stock units		0.1
Treasury stock purchased		0.0
Treasury stock purchased				(2.5)				(2.5)
Dividends to shareholders					(14.3)			(14.3)
Stockholders' Equity, Other					(0.1)		(0.1)	0.0
Balance (in shares) at Sep. 30, 2020		190.3
Balance at Sep. 30, 2020	$ 2,402.2	$ 2.0	$ 2,074.0	$ (214.7)	$ 850.3	$ (409.7)	$ 100.3	$ 2,402.2