Retirement Benefits - Components of Net Periodic Benefit Cost (Rationalization) (Details) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2018	[1]	Sep. 30, 2018	[1]	Jun. 30, 2018	[1]	Mar. 31, 2018	[1]	Dec. 31, 2017	[1]	Sep. 30, 2017	[1]	Jun. 30, 2017	[1]	Mar. 31, 2017	[1]	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Restructuring, Settlement and Impairment Provisions	$ 4,800		$ 300		$ 500		$ 700		$ 1,300		$ 600		$ 3,000		$ 900		$ 6,253	$ 5,826	$ 19,061
Special Termination Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Restructuring, Settlement and Impairment Provisions																	$ 0	$ 0	2,197
Special Termination Benefits [Member] | LaPorte, Indiana manufacturing facility [Member]
Defined Benefit Plan Disclosure [Line Items]
Restructuring, Settlement and Impairment Provisions																			2,800
Net Curtailment Gain [Member] | LaPorte, Indiana manufacturing facility [Member]
Defined Benefit Plan Disclosure [Line Items]
Restructuring, Settlement and Impairment Provisions																			$ (600)

[1] The first, second, third and fourth quarters of 2018 include rationalization charges of $0.7 million, $0.5 million, $0.3 million and $4.8 million, respectively. The second quarter of 2018 includes a loss on early extinguishment of debt of $2.5 million.