Stockholders' Equity - Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax			$ 5.8	$ (17.1)	$ (8.7)
Other comprehensive income (loss), tax effect			3.0	3.4	(1.2)
Other comprehensive income (loss)			8.8	(13.7)	(9.9)
Provision for income taxes			(11.4)	(29.6)	(29.4)
Pension plan settlement charge	$ 0.4	$ 0.2	0.6	0.8	0.0
SERP pension plan settlement charge			0.6	0.8	5.5
Cost Of Sales And Selling General And Administrative Expenses | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of products sold and selling, general, and admin expense			5.9	7.2	7.1
Provision for income taxes			2.3	2.8	2.7
Unrealized foreign currency translation gains (losses)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax			20.0	(7.1)	(15.0)
Other comprehensive income (loss), tax effect			0.0	0.4	0.0
Other comprehensive income (loss)			20.0	(6.7)	(15.0)
Unrealized loss on available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax			(0.4)	0.0	0.0
Other comprehensive income (loss), tax effect			0.1	0.0	0.0
Other comprehensive income (loss)			(0.3)	0.0	0.0
Adjustment to pension and other benefit liabilities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax			(13.8)	(10.0)	6.3
Other comprehensive income (loss), tax effect			2.9	3.0	(1.2)
Other comprehensive income (loss)			(10.9)	(7.0)	5.1
Adjustment to pension and other benefit liabilities | Pension Plan Settlement Charge | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, before tax				0.8	5.5
Reclassification from AOCI, tax			$ 0.2	$ 0.2	$ 2.1