Employee Benefit Plans - Assumptions Used to Calculate Net Periodic Benefit Cost for Domestic Defined Benefit Pension and Postretirement Benefit Plans (Detail)	6 Months Ended		12 Months Ended
	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pre-65
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate			7.00%	7.50%	8.50%
Ultimate cost trend rate			4.50%	4.50%	6.10%
Year that the rate reaches the ultimate cost trend rate:	2023		2023	2023	2030
Post-65
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate			8.30%	8.80%	7.50%
Ultimate cost trend rate			4.50%	4.50%	5.40%
Year that the rate reaches the ultimate cost trend rate:	2024		2024	2024	2030
Defined benefit pension plans
Defined Benefit Plan Disclosure [Line Items]
Discount rate			4.20%	3.80%	4.70%
Weighted average rate of future compensation increases				3.80%	3.80%
Long-term rate of return on plan assets	6.80%	7.50%	6.50%		8.00%
Postretirement benefit plans
Defined Benefit Plan Disclosure [Line Items]
Discount rate			4.20%	3.80%	4.70%
Annual increase in Medicare Part B premium			6.00%	6.00%	6.00%