General - Cash, Cash Equivalents and Restricted Cash Equivalents (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Cash and cash equivalents	$ 2,059	$ 2,008	$ 1,896
Restricted cash and restricted cash equivalents	220	170	51
Cash and restricted cash included in assets held for sale	0		113
Restricted cash and restricted cash equivalents included in long-term receivables and other assets, net	15		14
Cash, cash equivalents, restricted cash and restricted cash equivalents	$ 2,294	$ 2,194	$ 2,074	$ 3,574