Retirement Benefits - Pretax Amounts Recognized in Accumulated Other Comprehensive Income Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Prior service cost (credit)	$ 110	$ 135
Net loss	27,860	33,461
Total	27,970	33,596
Net gain (loss) in current year	(23)
Prior service cost	0
Amortization of prior service cost (credit)	24
Amortization of net loss (gain)	6,541
Exchange rate effect on amounts in OCI	0
Total	6,542
Non-U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Prior service cost (credit)	(77)	(38)
Net loss	(17,643)	15,330
Total	(17,720)	15,292
Net gain (loss) in current year	(5,367)
Prior service cost	0
Amortization of prior service cost (credit)	(15)
Amortization of net loss (gain)	1,239
Exchange rate effect on amounts in OCI	1,468
Total	(2,675)
Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Prior service cost (credit)	(849)	(1,215)
Net loss	(3,852)	(2,197)
Total	(4,701)	$ (3,412)
Net gain (loss) in current year	1,990
Prior service cost	0
Amortization of prior service cost (credit)	(366)
Amortization of net loss (gain)	(340)
Exchange rate effect on amounts in OCI	5
Total	$ 1,289