Summary of Significant Accounting Policies - EGTS - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2024 USD ($) operatingSegment	Dec. 31, 2023 USD ($)
Disaggregation of Revenue [Line Items]
Unbilled revenue	$ 807	$ 787
Number of reportable segments | operatingSegment	8
EGTS
Disaggregation of Revenue [Line Items]
Unbilled revenue		17
Contract assets	$ 7	8
Contract liabilities	$ 3	$ 2
Number of reportable segments | operatingSegment	1