Significant Accounting Policies - Summary of Future Lease Payments Under Non-Cancellable Leases (Details) $ in Millions	Jun. 30, 2019 USD ($)
Operating Lease Liabilities, Payments Due [Abstract]
2019 (excluding the six months ended June 30, 2019)	$ 10
2020	21
2021	20
2022	19
2023	12
Thereafter	12
Total future lease payments	94
Less imputed interest	(9)
Total lease liabilities	85
Accrued expenses and other current liabilities	18
Other long-term liabilities	67	[1]
Total lease liabilities	85
Finance Lease Liabilities, Payments, Due [Abstract]
2019 (excluding the six months ended June 30, 2019)	4
2020	9
2021	10
2022	10
2023	10
Thereafter	67
Total future lease payments	110
Less imputed interest	(25)
Total lease liabilities	85
Accrued expenses and other current liabilities	5
Other long-term liabilities	80	[1]
Total lease liabilities	$ 85

[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.