Consolidated Statements of Equity (unaudited) - USD ($) $ in Millions	Total	Common Stock and Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests
Balance, December 31, 2019 at Dec. 31, 2018	$ 337.0	$ 481.8	$ 676.7	$ (895.5)	$ 67.9	$ 6.1
Increase (Decrease) in Stockholders' Equity
Net income	24.6	0.0	24.7	0.0	0.0	(0.1)
Repurchase of common stock	(4.8)	0.0	0.0	(4.8)	0.0	0.0
Payments in consideration of employee tax obligations related to stock-based compensation	(4.3)	(4.3)	0.0	0.0	0.0	0.0
Stock-based compensation	1.9	1.9	0.0	0.0	0.0	0.0
Exercise of stock options	9.2	(2.2)	0.0	11.4	0.0	0.0
Shares issued	(0.3)	(7.4)	0.0	7.1	0.0	0.0
Dividends declared	(18.1)	0.0	(18.1)	0.0	0.0	0.0
Other comprehensive (loss) income	8.6	0.0	0.0	0.0	8.6	0.0
Balance, September 30, 2020 at Mar. 31, 2019	353.8	469.8	683.3	(881.8)	76.5	6.0
Balance, December 31, 2019 at Dec. 31, 2018	337.0	481.8	676.7	(895.5)	67.9	6.1
Increase (Decrease) in Stockholders' Equity
Net income	154.8
Other comprehensive (loss) income	17.4				17.4
Balance, September 30, 2020 at Sep. 30, 2019	451.7	475.4	776.9	(892.2)	85.3	6.3
Balance, December 31, 2019 at Mar. 31, 2019	353.8	469.8	683.3	(881.8)	76.5	6.0
Increase (Decrease) in Stockholders' Equity
Net income	76.4	0.0	76.2	0.0	0.0	0.2
Repurchase of common stock	(25.0)	0.0	0.0	(25.0)	0.0	0.0
Payments in consideration of employee tax obligations related to stock-based compensation	(0.6)	(0.6)	0.0	0.0	0.0	0.0
Stock-based compensation	3.7	3.7	0.0	0.0	0.0	0.0
Exercise of stock options	8.8	(2.4)	0.0	11.2	0.0	0.0
Shares issued	1.4	(0.5)	0.0	1.9	0.0	0.0
Dividends declared	(18.2)	0.0	(18.2)	0.0	0.0	0.0
Other comprehensive (loss) income	(13.0)	0.0	0.0	0.0	(13.0)	0.0
Balance, September 30, 2020 at Jun. 30, 2019	387.3	470.0	741.3	(893.7)	63.5	6.2
Increase (Decrease) in Stockholders' Equity
Net income	53.8	0.0	53.7	0.0	0.0	0.1
Stock-based compensation	5.8	5.8	0.0	0.0	0.0	0.0
Exercise of stock options	1.1	(0.4)	0.0	1.5	0.0	0.0
Dividends declared	(18.1)	0.0	(18.1)	0.0	0.0	0.0
Other comprehensive (loss) income	21.8	0.0	0.0	0.0	21.8	0.0
Balance, September 30, 2020 at Sep. 30, 2019	451.7	475.4	776.9	(892.2)	85.3	6.3
Balance, December 31, 2019 at Dec. 31, 2019	402.2	478.6	730.5	(892.2)	78.8	6.5
Increase (Decrease) in Stockholders' Equity
Net income	42.1	0.0	42.0	0.0	0.0	0.1
Repurchase of common stock	(40.4)	0.0	0.0	(40.4)	0.0	0.0
Payments in consideration of employee tax obligations related to stock-based compensation	(4.1)	(4.1)	0.0	0.0	0.0	0.0
Stock-based compensation	2.9	2.9	0.0	0.0	0.0	0.0
Shares issued	0.0	(10.3)	0.0	10.3	0.0	0.0
Dividends declared	(20.2)	0.0	(20.2)	0.0	0.0	0.0
Other comprehensive (loss) income	1.4	0.0	0.0	0.0	1.4	0.0
Balance, September 30, 2020 at Mar. 31, 2020	383.9	467.1	752.3	(922.3)	80.2	6.6
Balance, December 31, 2019 at Dec. 31, 2019	402.2	478.6	730.5	(892.2)	78.8	6.5
Increase (Decrease) in Stockholders' Equity
Net income	39.2
Other comprehensive (loss) income	(24.9)				(24.9)
Balance, September 30, 2020 at Sep. 30, 2020	320.5	471.1	712.1	(920.6)	53.9	4.0
Balance, December 31, 2019 at Mar. 31, 2020	383.9	467.1	752.3	(922.3)	80.2	6.6
Increase (Decrease) in Stockholders' Equity
Net income	(9.6)	0.0	(7.3)	0.0	0.0	(2.3)
Stock-based compensation	2.9	2.9	0.0	0.0	0.0	0.0
Shares issued	0.8	(0.7)	0.0	1.5	0.0	0.0
Dividends declared	(20.0)	0.0	(20.0)	0.0	0.0	0.0
Other comprehensive (loss) income	(8.4)	0.0	0.0	0.0	(8.4)	0.0
Balance, September 30, 2020 at Jun. 30, 2020	349.6	469.3	725.0	(920.8)	71.8	4.3
Increase (Decrease) in Stockholders' Equity
Net income	6.7	0.0	7.0	0.0	0.0	(0.3)
Stock-based compensation	2.0	2.0	0.0	0.0	0.0	0.0
Shares issued	0.0	(0.2)	0.0	0.2	0.0	0.0
Dividends declared	(19.9)	0.0	(19.9)	0.0	0.0	0.0
Other comprehensive (loss) income	(17.9)	0.0	0.0	0.0	(17.9)	0.0
Balance, September 30, 2020 at Sep. 30, 2020	$ 320.5	$ 471.1	$ 712.1	$ (920.6)	$ 53.9	$ 4.0