Stockholders' Equity - Components of AOCI (Details) - USD ($) $ in Millions	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Jun. 30, 2023	May 18, 2023	May 17, 2023	Dec. 31, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Equity	$ 2,572	$ 2,766	$ 2,534	$ 2,460	$ 2,431	$ 2,431
Accumulated other comprehensive income (loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Equity	(29)	$ (27)	$ (23)	(3)	$ 0	$ 0	$ (167)
Available-for-sale securities unrealized gain (loss), net
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Equity	(1)			(3)
Postretirement benefit actuarial gain (loss), net
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Equity	$ (28)			$ 0