Pensions - Weighted Average Assumptions Used to Determine Benefit Obligations (Detail)	Dec. 31, 2017	Dec. 31, 2016
Domestic Plan [Member]
Weighted average assumptions used to determine benefit obligations
Discount rate	3.55%	3.95%
Foreign Plan [Member]
Weighted average assumptions used to determine benefit obligations
Discount rate	3.40%	3.70%
Pension Plan [Member] | Domestic Plan [Member]
Weighted average assumptions used to determine benefit obligations
Discount rate	3.55%	3.99%
Pension Plan [Member] | Foreign Plan [Member]
Weighted average assumptions used to determine benefit obligations
Discount rate	2.17%	2.23%
Rate of compensation increase	3.17%	3.15%