Pension and Other Benefit Plans - Defined Benefit Plan Weighted Average Assumptions Used in Calculating Benefit Obligation and Net Periodic Benefit Cost For US Postretirement Medical Plan (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Pension Plans Postretirement And Other Employee Benefits [Line Items]
Discount rate	4.25%	4.25%
Return on plan assets	0.00%
Current medical cost trend rate	7.50%	7.50%
Ultimate medical cost trend rate	5.00%	5.00%
Year that the rate reaches the ultimate trend rate	2023	2023
Postretirement medical plan
Pension Plans Postretirement And Other Employee Benefits [Line Items]
Discount rate	5.00%	5.00%	5.50%
Return on plan assets	7.00%	7.00%	7.00%
Current medical cost trend rate	8.00%	8.00%	8.00%
Ultimate medical cost trend rate	5.00%	5.00%	5.00%
Year that the rate reaches the ultimate trend rate	2023	2018	2017