Lease Obligations - Schedule of Lease Cost (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Finance lease cost
Net lease cost	$ 43
SG&A [Member]
Lessee Lease Description [Line Items]
Operating lease cost	21	[1]
Cost of operations [Member]
Lessee Lease Description [Line Items]
Operating lease cost	19	[1]
Finance lease cost
Amortization of leased assets	2
Interest expense, net [Member]
Finance lease cost
Interest on lease liabilities	$ 1

[1] Includes short-term leases and immaterial variable lease costs.