Long term debt and interest expense, net - Deferred Financing (Details) - Deferred financing - USD ($) $ in Millions	1 Months Ended
Dec. 31, 2019	Dec. 31, 2020
Long-term debt and interest expenses
Long-term debt	$ 33	$ 32
Properties in Palo Alto, California
Long-term debt and interest expenses
Net proceeds	291
Long-term debt	$ 33
Lease term	10 years
Weighted average discount rate	4.62%

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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