Pension and Other Post-Retirement Benefits - Pension Obligations, Plan Assets, and Other Post-retirement Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Change in Benefit Obligation
Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits			$ 9.0
Change in Fair Value of Plan Assets
Plan assets at beginning of year	$ 413.5
Company contributions	1.9	$ 1.8	1.9
Plan assets at end of year	435.6	413.5
Amount Recognized
Other liabilities	(84.4)	(82.3)
Accumulative other comprehensive loss:
After-tax amount recognized in accumulated other comprehensive loss	83.6	87.1	99.9	$ 107.7
Defined Benefit Pension [Member]
Change in Benefit Obligation
Benefit obligation at beginning of year	464.4	475.0
Service cost	6.5	6.1	7.4
Interest cost	15.4	15.3	19.6
Actuarial loss	(34.8)	(18.3)
Benefits paid	44.2	44.5
Effect of foreign exchange rate changes	3.2	(5.8)
Benefit obligation at end of year	480.1	464.4	475.0
Change in Fair Value of Plan Assets
Plan assets at beginning of year	413.5	416.1
Actual return on plan assets	61.3	45.8
Effect of exchange rate changes	3.4	(6.1)
Company contributions	1.6	2.2
Benefits paid	(44.2)	(44.5)
Plan assets at end of year	435.6	413.5	416.1
Funded Status at end of year	(44.5)	(50.9)
Amount Recognized
Other liabilities	(44.5)	(50.9)
Accumulative other comprehensive loss:
Net actuarial loss	132.5	144.1
Prior service credit (cost)	(0.1)	(0.1)
Accumulated other comprehensive loss	132.4	144.0
Defined Benefit Plan, Amounts Recognized in Balance Sheet and Accumulated Other Comprehensive Income (Loss)	87.9	93.1
After-tax amount recognized in accumulated other comprehensive loss	82.7	90.0
Retiree Health and Life [Member]
Change in Benefit Obligation
Benefit obligation at beginning of year	30.3	35.0
Service cost	0.2	0.2	0.2
Interest cost	1.1	0.9	1.3
Actuarial loss	(5.5)	3.0
Benefits paid	3.4	2.8
Effect of foreign exchange rate changes	0.0	0.0
Benefit obligation at end of year	33.7	30.3	35.0
Change in Fair Value of Plan Assets
Plan assets at beginning of year	0.0	0.0
Actual return on plan assets	0.0	0.0
Effect of exchange rate changes	0.0	0.0
Company contributions	3.4	2.8
Benefits paid	(3.4)	(2.8)
Plan assets at end of year	0.0	0.0	$ 0.0
Funded Status at end of year	(33.7)	(30.3)
Amount Recognized
Other liabilities	(33.7)	(30.3)
Accumulative other comprehensive loss:
Net actuarial loss	2.8	(2.9)
Prior service credit (cost)	(1.6)	(1.8)
Accumulated other comprehensive loss	1.2	(4.7)
Defined Benefit Plan, Amounts Recognized in Balance Sheet and Accumulated Other Comprehensive Income (Loss)	(32.5)	(35.0)
After-tax amount recognized in accumulated other comprehensive loss	0.9	(2.9)
Other Pension Plan [Member]
Change in Benefit Obligation
Benefit obligation at beginning of year	$ 30.3
Benefit obligation at end of year		$ 30.3