Retirement Benefits - Weighted Average Actuarial Assumptions to Determine Benefit Obligations (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.20%	2.10%
Rate of compensation increase	3.30%	3.30%
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.50%	3.80%
Expected return on plan assets	8.50%	8.50%	8.50%
Rate of compensation increase	2.60%	2.60%
Assumed for next year	6.40%	6.20%
Ultimate rate	4.30%	4.90%
Year that the ultimate rate is reached	2035	2047