Pension and Other Postretirement Benefits - Cash Flow (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Minimum Cash Contributions, Next Fiscal Year	$ 9,900
Expected Benefit Payments, Next Twelve Months	6,678
Expected Benefit Payments, Year Two	6,804
Expected Benefit Payments, Year Three	6,810
Expected Benefit Payments, Year Four	7,481
Expected Benefit Payments, Year Five	7,511
Expected Benefit Payments, Five Fiscal Years Thereafter	41,709
Domestic [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Minimum Cash Contributions, Next Fiscal Year	4,600
Expected Benefit Payments, Next Twelve Months	4,473
Expected Benefit Payments, Year Two	4,420
Expected Benefit Payments, Year Three	4,187
Expected Benefit Payments, Year Four	4,159
Expected Benefit Payments, Year Five	4,165
Expected Benefit Payments, Five Fiscal Years Thereafter	22,218
Domestic [Member] | Other Postretirement Benefit Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Minimum Cash Contributions, Next Fiscal Year	400
Expected Benefit Payments, Next Twelve Months	459
Expected Benefit Payments, Year Two	441
Expected Benefit Payments, Year Three	416
Expected Benefit Payments, Year Four	489
Expected Benefit Payments, Year Five	364
Expected Benefit Payments, Five Fiscal Years Thereafter	1,502
Foreign [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Minimum Cash Contributions, Next Fiscal Year	5,300
Expected Benefit Payments, Next Twelve Months	2,205
Expected Benefit Payments, Year Two	2,384
Expected Benefit Payments, Year Three	2,623
Expected Benefit Payments, Year Four	3,322
Expected Benefit Payments, Year Five	3,346
Expected Benefit Payments, Five Fiscal Years Thereafter	$ 19,491