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
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 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, 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