Defined Benefit Plans - Schedule of Assumptions Used (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Weighted-Average Assumptions Used to Determine Net Cost for Years Ended December 31:
Expected long-term rate of return on plan assets	6.80%
Pension Benefits [Member]
Weighted-Average Assumptions Used to Determine Benefit Obligations at December 31:
Discount rate	4.60%	4.20%
Rate of compensation increase	4.00%	4.00%
Weighted-Average Assumptions Used to Determine Net Cost for Years Ended December 31:
Discount rate	4.20%	5.00%	4.20%
Expected long-term rate of return on plan assets	6.80%	7.40%	7.80%
Rate of compensation increase	4.00%	4.00%	4.00%
Postretirement Benefits [Member]
Weighted-Average Assumptions Used to Determine Benefit Obligations at December 31:
Discount rate	4.10%	3.50%
Weighted-Average Assumptions Used to Determine Net Cost for Years Ended December 31:
Discount rate	3.50%	4.30%	3.70%