Retirement Benefits - Pension Plan Weighted Average Asset Allocations (Details) - Pension Benefit Plan	Dec. 31, 2018	Dec. 31, 2017
U.S. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan securities	100.00%	100.00%
U.S. Plans | Equity Securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan securities	9.00%	47.00%
U.S. Plans | Fixed Income Securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan securities	90.00%	51.00%
U.S. Plans | Cash/Commingled Funds/Other
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan securities	1.00%	2.00%
Non-U.S. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan securities	100.00%	100.00%
Non-U.S. Plans | Equity Securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan securities	13.00%	14.00%
Non-U.S. Plans | Fixed Income Securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan securities	31.00%	30.00%
Non-U.S. Plans | Cash/Commingled Funds/Other
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan securities	56.00%	56.00%