Pensions and Other Post-Retirement Benefits - Weighted Average Assumptions Underlying Pension Computations (Detail)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net periodic pension costs:
Weighted average expected long term rate of return	4.30%	4.40%	4.60%
The Netherlands
Pension benefit obligation:
Pension benefit obligation - discount rate	1.50%	2.00%	1.90%
Pension benefit obligation - rate of compensation increase		1.80%	1.80%
Net periodic pension costs:
Net periodic pension costs - discount rate	2.00%	1.90%	1.80%
Net periodic pension costs - rate of compensation increase	1.80%	1.80%	3.80%
Weighted average expected long term rate of return	3.50%	3.60%	3.80%
Other
Pension benefit obligation:
Pension benefit obligation - discount rate	1.90%	2.50%	2.30%
Pension benefit obligation - rate of compensation increase	1.10%	1.10%	1.10%
Net periodic pension costs:
Net periodic pension costs - discount rate	2.50%	2.30%	2.30%
Net periodic pension costs - rate of compensation increase	1.10%	1.10%	1.10%
Weighted average expected long term rate of return	4.20%	4.30%	4.40%
United States
Pension benefit obligation:
Pension benefit obligation - discount rate	3.40%	4.40%	3.70%
Net periodic pension costs:
Net periodic pension costs - discount rate	4.40%	3.70%	4.40%
Weighted average expected long term rate of return	6.70%	6.90%	7.00%