Weighted-Average Assumptions Used to Determine Benefit Obligation (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Schedule of Benefit Obligations Weighted Average Assumptions [Line Items]
Discount rate per annum	7.75%	8.50%
Discount rate for Years ended Dec 31, 2016 and 2015	7.75% per annum for 2016 and 8.5% per annum for 2015
Long-term rate of compensation increase for Years ended Dec 31, 2015 and 2014	11% per annum for first year, 10% for next five years and 7% thereafter
First Year
Schedule of Benefit Obligations Weighted Average Assumptions [Line Items]
Long-term rate of compensation increase per annum	11.00%	11.00%
Next Five Years
Schedule of Benefit Obligations Weighted Average Assumptions [Line Items]
Long-term rate of compensation increase per annum	10.00%	10.00%
There After
Schedule of Benefit Obligations Weighted Average Assumptions [Line Items]
Long-term rate of compensation increase per annum	7.00%	7.00%