PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS - Components of Net Periodic Benefit Costs (Credits) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Pension
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 13	$ 15
Interest cost	68	65
Expected return on plan assets	(123)	(118)
Amortization of actuarial loss	38	44
Amortization of prior service cost (credit)	1	1
Accelerated pension costs included in Plum Creek merger-related costs	5	0
Total net periodic benefit cost (credit)	2	7
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Interest cost	2	3
Amortization of actuarial loss	2	2
Amortization of prior service cost (credit)	(2)	(2)
Total net periodic benefit cost (credit)	2	3
Plum Creek [Member]
Defined Benefit Plan Disclosure [Line Items]
Accelerated pension costs included in Plum Creek merger-related costs	$ 5	$ 0