Weighted Average Actuarial Assumptions to Determine Net Period Cost (Detail) (United States Pension Plan of US Entity [Member])	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
United States Pension Plan of US Entity [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.90%	4.10%	4.60%
Expected return on plan assets	8.50%	8.50%	8.50%
Rate of compensation increase	3.00%	3.10%	3.10%
Health care cost trend rate	7.20%	7.20%	7.80%