Summary of Significant Accounting Policies - MEC - Reconciliation of Cash (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 1,591	$ 1,096
Investments and restricted cash and cash equivalents	173	127
Total cash and cash equivalents and restricted cash and cash equivalents	1,817	1,244	$ 1,445	$ 1,268
MEC
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	258	232
Investments and restricted cash and cash equivalents	10	7
Total cash and cash equivalents and restricted cash and cash equivalents	$ 268	$ 239	$ 45	$ 330