Lease Obligations - Schedule of Lease Cost (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Finance lease cost
Net lease cost		$ 34	$ 39
SG&A expenses [Member]
Lessee Lease Description [Line Items]
Operating lease cost	[1]	11	12
Cost of operations [Member]
Lessee Lease Description [Line Items]
Operating lease cost	[1]	22	24
Finance lease cost
Amortization of leased assets			2
Net interest expense [Member]
Finance lease cost
Interest on lease liabilities		$ 1	$ 1

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