Fair Value of Financial Instruments - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total	$ 1,606	$ 1,824
Money market funds (Cash and cash equivalents & restricted cash) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial assets, Fair Value	1,632	1,813
Interest Rate Swap Asset (Liability) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial assets, Fair Value	1	12
Financial liabilities, Fair Value	(27)	(1)
Level I [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total	1,632	1,813
Level I [Member] \| Money market funds (Cash and cash equivalents & restricted cash) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial assets, Fair Value	1,632	1,813
Level II [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total	(26)	11
Level II [Member] \| Interest Rate Swap Asset (Liability) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial assets, Fair Value	1	12
Financial liabilities, Fair Value	$ (27)	$ (1)