Derivatives and Other Financial Instruments - Schedule of Carrying Values and Fair Values of Other Financial Instruments (Detail) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Carrying Value [Member]
Derivative [Line Items]
Cash and cash equivalents	$ 1,017	$ 1,113
Restricted cash	3	3
Long-term debt due within one year	1	1
Long-term debt, less amount due within one year	1,802	1,801
Fair Value [Member]
Derivative [Line Items]
Cash and cash equivalents	1,017	1,113
Restricted cash	3	3
Long-term debt due within one year	1	1
Long-term debt, less amount due within one year	$ 1,939	$ 1,863