CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Treasury Stock	Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss) Income	Non-controlling Interest in Subsidiaries
Balance at beginning of period at Dec. 31, 2016	$ 7.6
Increase (Decrease) in Temporary Equity [Roll Forward]
Net income (loss) attributable to noncontrolling interests	(5.4)
Balance at end of period at Dec. 31, 2017	2.2
Balance at beginning of period (in shares) at Dec. 31, 2016		99.2	44.8
Balance at beginning of period at Dec. 31, 2016	(41.9)	$ 1.0	$ (1,700.0)	$ 492.8	$ 1,264.8	$ (103.5)	$ 3.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	151.4				151.4
Net loss attributable to non-controlling interests	(5.3)						(5.3)
Acquisition of non-controlling interest in subsidiary	(0.9)			(3.2)			2.3
Adjustment to pension liability, net of tax	(0.5)					(0.5)
Unrealized loss on cash flow hedging derivatives, net of tax	(0.6)					(0.6)
Foreign currency adjustments	29.1					29.1
Exercise of stock options (in shares)			(0.3)
Exercise of stock options	12.8		$ 4.5	8.3
Issuances of PRSUs, RSUs and DSUs (shares)			(0.2)
Issuances of PRSUs, RSUs, and DSUs	$ 0.0		$ 3.2	(3.2)
Treasury stock repurchased (in shares)	0.6		0.6
Treasury stock repurchased	$ (40.1)		$ (40.1)
Treasury stock repurchased - PRSU/RSU/DSU releases (in shares)			0.1
Treasury stock repurchased - PRSU/RSU/DSU releases	(4.8)		$ (4.8)
Amortization of unearned stock-based compensation	13.3			13.3
Balance at end of period (in shares) at Dec. 31, 2017		99.2	45.0
Balance at ending of period at Dec. 31, 2017	112.5	$ 1.0	$ (1,737.2)	508.0	1,416.2	(75.5)	0.0
Increase (Decrease) in Temporary Equity [Roll Forward]
Net income (loss) attributable to noncontrolling interests	(2.7)
Acquisition of non-controlling interest in subsidiary	3.1						3.1
Balance at end of period at Dec. 31, 2018	0.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	100.5				100.5
Net loss attributable to non-controlling interests	(0.2)						(0.2)
Acquisition of non-controlling interest in subsidiary	(0.5)			(0.5)
Adjustment to pension liability, net of tax	(0.4)					(0.4)
Unrealized loss on cash flow hedging derivatives, net of tax	0.0
Foreign currency adjustments	(18.9)					(18.9)
Exercise of stock options (in shares)			(0.2)
Exercise of stock options	4.6		$ 2.1	2.5
Issuances of PRSUs, RSUs and DSUs (shares)			(0.2)
Issuances of PRSUs, RSUs, and DSUs	0.0		$ 2.7	(2.7)
Treasury stock repurchased - PRSU/RSU/DSU releases (in shares)			0.1
Treasury stock repurchased - PRSU/RSU/DSU releases	(4.6)		$ (4.6)
Amortization of unearned stock-based compensation	24.8			24.8
Acquisition of non-controlling interest	0.5
Balance at end of period (in shares) at Dec. 31, 2018		99.2	44.7
Balance at ending of period at Dec. 31, 2018	217.5	$ 1.0	$ (1,737.0)	532.1	1,513.8	(95.3)	2.9
Balance at end of period at Dec. 31, 2019	0.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	189.5				189.5
Net loss attributable to non-controlling interests	(0.1)						(0.1)
Acquisition of non-controlling interest in subsidiary	(1.9)						(1.9)
Adjustment to pension liability, net of tax	(1.9)					(1.9)
Unrealized loss on cash flow hedging derivatives, net of tax	0.0
Foreign currency adjustments	9.5					9.5
Exercise of stock options (in shares)			(0.3)
Exercise of stock options	17.8		$ 4.8	13.0
Issuances of PRSUs, RSUs and DSUs (shares)			(0.3)
Issuances of PRSUs, RSUs, and DSUs	$ 0.0		$ 3.7	(3.7)
Treasury stock repurchased (in shares)	1.3		1.3
Treasury stock repurchased	$ (102.3)		$ (102.3)
Treasury stock repurchased - PRSU/RSU/DSU releases (in shares)			0.1
Treasury stock repurchased - PRSU/RSU/DSU releases	(3.4)		$ (3.4)
Amortization of unearned stock-based compensation	26.8			26.8
Charitable stock donation	8.9		$ 1.4	7.5
Charitable stock donation (in shares)			(0.1)
Balance at end of period (in shares) at Dec. 31, 2019		99.2	45.4
Balance at ending of period at Dec. 31, 2019	$ 360.4	$ 1.0	$ (1,832.8)	$ 575.7	$ 1,703.3	$ (87.7)	$ 0.9