Pensions and Postretirement Benefits Other than Pensions - Weighted Average Assumptions Used to Determine Benefit Obligations (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate (as a percent)	3.20%	3.54%
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate (as a percent)	3.50%	3.95%
United States | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate (as a percent)	3.50%	3.90%
United States | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate (as a percent)	3.50%	3.95%
Foreign Plan | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate (as a percent)	2.50%	2.65%
Foreign Plan | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate (as a percent)	0.00%	0.00%