Summarization of Bases Used to Measure Fair Value of Financial Instruments (Detail) - Approximate fair values - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Current maturities of long-term debt and lease obligations	$ 3	$ 3
Long-term debt and lease obligations	3,564	3,595
Total liabilities	3,567	3,598
Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Current maturities of long-term debt and lease obligations	3	3
Long-term debt and lease obligations	3,564	3,595
Total liabilities	$ 3,567	$ 3,598