Summary of Significant Accounting Policies - LIFO Inventory (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Summary of Accounting Policies [Line Items]
LIFO inventory	$ 106	$ 101
Cost of replacing inventories carried at LIFO cost less than carrying value	8
CERC Corp
Summary of Accounting Policies [Line Items]
LIFO inventory	86	$ 82
Cost of replacing inventories carried at LIFO cost less than carrying value	$ 13