Pension - Narrative (Details) $ in Millions	9 Months Ended
	Sep. 30, 2018 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Expected employer contributions to pension and other postretirement benefit plans in current year	$ 20.1
Employer contributions made	15.5
Domestic Plan
Defined Benefit Plan Disclosure [Line Items]
Expected employer contributions to pension and other postretirement benefit plans in current year	$ 15.5