Summary of Significant Accounting Policies - Changes in the Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-tax	$ (2.9)	$ (31.3)	$ 52.0
Tax	4.8	(3.8)	(2.1)
Other comprehensive income (loss)	1.9	(30.2)	49.9
Other comprehensive (loss) income		(35.1)
Pension and OPEB liability adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-tax	2.5	(0.9)	15.4
Tax	1.4	(2.4)	(3.8)
Other comprehensive income (loss)	3.9	(3.3)	11.6
Derivative instrument adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-tax	(2.9)
Tax	0.0
Other comprehensive income (loss)	(2.9)
Derivative instrument adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-tax		(2.4)	5.1
Tax		1.4	(2.8)
Other comprehensive income (loss)		(1.0)	2.3
Unrealized foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-tax	(2.5)	(28.0)	31.5
Tax	3.4	(2.8)	4.5
Other comprehensive income (loss)	$ 0.9	(30.8)	$ 36.0
Accounting Standards Update 2018-02
Accumulated Other Comprehensive Income (Loss) [Line Items]
New accounting pronouncement or change in accounting principle, cumulative effect of change on equity or net assets		$ 4.9