Financial Instruments - Contractual Maturities (Details) $ in Millions	Jun. 30, 2021 USD ($)
Amortized Cost
Due within one year	$ 50,515
Due after one year through five years	22,210
Due after five years through ten years	1,445
Due after ten years	3,637
Amortized cost	77,807
Estimated Fair Value
Due within one year	50,530
Due after one year through five years	22,382
Due after five years through ten years	1,450
Due after ten years	3,651
Estimated fair value	$ 78,013