Pensions and Postretirement Benefits Other Than Pensions - Weighted Average Asset Allocations for Domestic and U.K. Pension Plans' Assets (Detail)	Dec. 31, 2017	Dec. 31, 2016
United States
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations (as a percent)	100.00%	100.00%
United States | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations (as a percent)	52.00%	36.00%
United States | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations (as a percent)	40.00%	63.00%
United States | Other investments
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations (as a percent)	6.00%	0.00%
United States | Cash
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations (as a percent)	2.00%	1.00%
Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations (as a percent)	100.00%	100.00%
Foreign Plan | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations (as a percent)	68.00%	68.00%
Foreign Plan | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations (as a percent)	18.00%	18.00%
Foreign Plan | Other investments
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations (as a percent)	13.00%	14.00%
Foreign Plan | Cash
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations (as a percent)	1.00%	0.00%