v3.19.3
Investments and Fair Value Measurement - Fair Value of Unobservable Inputs, Assets (Details) - USD ($)
$ in Millions
6 Months Ended 9 Months Ended
Jun. 30, 2019
Sep. 30, 2019
Debt Securities    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Balance as of December 31, 2018 $ 2,370 $ 2,370
Total net gains (losses)    
Included in earnings   (8)
Included in other comprehensive income (loss)   0
Purchases   4
Transfers   0
Balance as of September 30, 2019   2,366
Non-marketable equity securities    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Balance as of December 31, 2018 0 0
Total net gains (losses)    
Included in earnings 22 (12)
Included in other comprehensive income (loss)   0
Purchases   11
Transfers   88
Balance as of September 30, 2019   $ 87
Warrants vested during period $ 35