Significant Accounting Policies - Summary of Future Lease Payments Under Non-Cancellable Leases (Details) $ in Millions	Sep. 30, 2019 USD ($)
Operating Lease Liabilities, Payments Due [Abstract]
2019 (excluding the nine months ended September 30, 2019)	$ 4
2020	23
2021	21
2022	19
2023	13
Thereafter	14
Total future lease payments	94
Less imputed interest	(9)
Total lease liabilities	85
Accrued expenses and other current liabilities	19
Other long-term liabilities	66	[1]
Total lease liabilities	85
Finance Lease Liabilities, Payments, Due [Abstract]
2019 (excluding the nine months ended September 30, 2019)	2
2020	9
2021	10
2022	10
2023	10
Thereafter	67
Total future lease payments	108
Less imputed interest	(24)
Total lease liabilities	84
Accrued expenses and other current liabilities	5
Other long-term liabilities	79	[1]
Total lease liabilities	$ 84

[1] Refer to “Note 2: Significant Accounting Policies” for additional information on our lease information, including transition accounting and updated accounting policy for leases upon adoption of ASC 842.