Summary of Significant Accounting Policies - Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Cash and cash equivalents	$ 5,552	$ 4,111
Restricted cash and cash equivalents	2,583	1,694
Total cash, cash equivalents and restricted cash and cash equivalents in the consolidated statements of cash flows	$ 8,135	$ 5,805	$ 6,265	$ 4,138