Income Taxes - Taxes Receivable (Payable) Table (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Components of Income Tax Receivable (Payable) [Line Items]
Income taxes receivable	$ 154	$ 247
Income taxes (payable)	(71)	(6)
Total net income taxes receivable (payable)	83	241
Accounts Receivable - Other [Member]
Components of Income Tax Receivable (Payable) [Line Items]
Income taxes receivable	53	180
Other Assets [Member]
Components of Income Tax Receivable (Payable) [Line Items]
Income taxes receivable, noncurrent	101	67
Accrued Expense [Member]
Components of Income Tax Receivable (Payable) [Line Items]
Income taxes (payable)	$ (71)	$ (6)