Pensions - Weighted Average Assumptions Used to Determine Net Periodic Benefit Costs (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Domestic Plan [Member]
Weighted-average assumptions used to determine net periodic benefit costs
Discount rate	3.95%	4.20%	3.85%
Foreign Plan [Member]
Weighted-average assumptions used to determine net periodic benefit costs
Discount rate	3.70%	4.00%	3.90%
Pension Plan [Member] | Domestic Plan [Member]
Weighted-average assumptions used to determine net periodic benefit costs
Discount rate	3.99%	4.24%	3.94%
Expected return on plan assets	6.60%	6.60%	6.70%
Pension Plan [Member] | Foreign Plan [Member]
Weighted-average assumptions used to determine net periodic benefit costs
Discount rate	2.23%	2.80%	2.66%
Expected return on plan assets	5.94%	4.39%	4.80%
Rate of compensation increase	3.15%	3.15%	3.11%