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
Beginning balance at Dec. 31, 2017	$ 263.3	$ 475.5	$ 573.1	$ (832.1)	$ 39.9	$ 6.9
Increase (Decrease) in Stockholders' Equity
Net income	43.4	0.0	43.6	0.0	0.0	(0.2)
Repurchase of common stock	(35.0)	0.0	0.0	(35.0)	0.0	0.0
Payments in consideration of employee tax obligations related to stock-based compensation	(0.7)	(0.7)	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	0.8	(0.4)	0.0	1.2	0.0	0.0
Shares issued	0.0	(1.3)	0.0	1.3	0.0	0.0
Dividends declared	(16.2)	0.0	(16.2)	0.0	0.0	0.0
Other comprehensive (loss) income	(16.6)	0.0	0.0	0.0	(16.6)	0.0
Ending balance at Mar. 31, 2018	245.9	476.8	603.7	(864.6)	23.3	6.7
Beginning balance at Dec. 31, 2017	263.3	475.5	573.1	(832.1)	39.9	6.9
Increase (Decrease) in Stockholders' Equity
Net income	82.0
Other comprehensive (loss) income	15.9
Ending balance at Jun. 30, 2018	294.9	472.8	625.5	(865.7)	55.8	6.5
Increase (Decrease) in Stockholders' Equity
Adjustment to retained earnings for adoption of ASC 606 | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]	3.2	0.0	3.2	0.0	0.0	0.0
Beginning balance at Mar. 31, 2018	245.9	476.8	603.7	(864.6)	23.3	6.7
Increase (Decrease) in Stockholders' Equity
Net income	38.6	0.0	38.8	0.0	0.0	(0.2)
Repurchase of common stock	(14.8)	0.0	0.0	(14.8)	0.0	0.0
Payments in consideration of employee tax obligations related to stock-based compensation	(2.3)	(2.3)	0.0	0.0	0.0	0.0
Stock-based compensation	5.9	5.9	0.0	0.0	0.0	0.0
Exercise of stock options	5.3	(3.7)	0.0	9.0	0.0	0.0
Shares issued	0.8	(3.9)	0.0	4.7	0.0	0.0
Dividends declared	(16.3)	0.0	(16.3)	0.0	0.0	0.0
Other comprehensive (loss) income	32.5	0.0	0.0	0.0	32.5	0.0
Ending balance at Jun. 30, 2018	294.9	472.8	625.5	(865.7)	55.8	6.5
Increase (Decrease) in Stockholders' Equity
Adjustment to retained earnings for adoption of ASC 606 | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]	(0.7)	0.0	(0.7)	0.0	0.0	0.0
Beginning balance 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
Ending balance at Mar. 31, 2019	353.8	469.8	683.3	(881.8)	76.5	6.0
Beginning balance at Dec. 31, 2018	337.0	481.8	676.7	(895.5)	67.9	6.1
Increase (Decrease) in Stockholders' Equity
Net income	101.0
Other comprehensive (loss) income	(4.4)
Ending balance at Jun. 30, 2019	387.3	470.0	741.3	(893.7)	63.5	6.2
Beginning balance 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
Ending balance at Jun. 30, 2019	$ 387.3	$ 470.0	$ 741.3	$ (893.7)	$ 63.5	$ 6.2