Long-Term Employee Benefit Liabilities - Summary of Weighted Average Significant Actuarial Assumptions Adopted in Measuring Company's Obligations and Cost (Detail) - Pension Plan, Defined Benefit [Member]	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.90%	3.10%
Rate of compensation increase	2.60%	2.30%
Net periodic benefit cost Discount rate	3.10%	3.20%
Rate of compensation increase	2.50%	2.40%
Expected return on plan assets	5.80%	5.80%

Long-Term Employee Benefit Liabilities - Summary of Weighted Average Significant Actuarial Assumptions Adopted in Measuring Company's Obligations and Cost (Detail) - Pension Plan, Defined Benefit [Member]

12 Months Ended

Dec. 31, 2017

Dec. 31, 2016

Defined Benefit Plan Disclosure [Line Items]

Discount rate

2.90%

3.10%

Rate of compensation increase

2.60%

2.30%

Net periodic benefit cost Discount rate

3.10%

3.20%

Rate of compensation increase

2.50%

2.40%

Expected return on plan assets

5.80%