Segment Information - Revenues and Intersegment Revenues (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Revenue	$ 2,879	$ 2,778	$ 2,714
Operating Segments | AST
Segment Reporting Information [Line Items]
Revenue	970	940	781
Operating Segments | NC&C
Segment Reporting Information [Line Items]
Revenue	972	1,026	1,053
Operating Segments | IMS
Segment Reporting Information [Line Items]
Revenue	959	834	917
Corporate & Eliminations
Segment Reporting Information [Line Items]
Revenue	(22)	(22)	(37)
Corporate & Eliminations | AST
Segment Reporting Information [Line Items]
Revenue	14	12	12
Corporate & Eliminations | NC&C
Segment Reporting Information [Line Items]
Revenue	7	9	24
Corporate & Eliminations | IMS
Segment Reporting Information [Line Items]
Revenue	$ 1	$ 1	$ 1