Significant Accounting Policies - Future Minimum Commitments Under Our corporate Headquarters Lease and Other Non-Cancelable Operating Leases (Parenthetical) (Details) $ in Millions	Dec. 31, 2018 USD ($)
Accounting Policies [Abstract]
Other long-term liabilities under financial obligation	$ 83	[1]

[1] Refer to “Note 2: Significant Accounting Policies” for further information regarding our leases, including the transition accounting and updated accounting policies upon adoption of ASC 842 in 2019.