Segment Information - Disaggregation of Revenue by Major End Market Served (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue, Major Customer [Line Items]
Sales	$ 1,283	$ 1,134	$ 3,687	$ 4,021
Third-party sales
Revenue, Major Customer [Line Items]
Sales	1,283	1,134	3,687	4,019
Third-party sales | Engine Products
Revenue, Major Customer [Line Items]
Sales	599	485	1,677	1,851
Third-party sales | Fastening Systems
Revenue, Major Customer [Line Items]
Sales	254	271	788	982
Third-party sales | Engineered Structures
Revenue, Major Customer [Line Items]
Sales	199	206	535	710
Third-party sales | Forged Wheels
Revenue, Major Customer [Line Items]
Sales	231	172	687	476
Third-party sales | Aerospace - Commercial
Revenue, Major Customer [Line Items]
Sales	543	472	1,466	2,100
Third-party sales | Aerospace - Commercial | Engine Products
Revenue, Major Customer [Line Items]
Sales	299	199	786	1,018
Third-party sales | Aerospace - Commercial | Fastening Systems
Revenue, Major Customer [Line Items]
Sales	126	169	403	650
Third-party sales | Aerospace - Commercial | Engineered Structures
Revenue, Major Customer [Line Items]
Sales	118	104	277	432
Third-party sales | Aerospace - Commercial | Forged Wheels
Revenue, Major Customer [Line Items]
Sales	0	0	0	0
Third-party sales | Aerospace - Defense
Revenue, Major Customer [Line Items]
Sales	232	261	728	730
Third-party sales | Aerospace - Defense | Engine Products
Revenue, Major Customer [Line Items]
Sales	130	142	402	394
Third-party sales | Aerospace - Defense | Fastening Systems
Revenue, Major Customer [Line Items]
Sales	37	37	120	120
Third-party sales | Aerospace - Defense | Engineered Structures
Revenue, Major Customer [Line Items]
Sales	65	82	206	216
Third-party sales | Aerospace - Defense | Forged Wheels
Revenue, Major Customer [Line Items]
Sales	0	0	0	0
Third-party sales | Commercial Transportation
Revenue, Major Customer [Line Items]
Sales	290	210	841	594
Third-party sales | Commercial Transportation | Engine Products
Revenue, Major Customer [Line Items]
Sales	0	0	0	0
Third-party sales | Commercial Transportation | Fastening Systems
Revenue, Major Customer [Line Items]
Sales	59	38	154	118
Third-party sales | Commercial Transportation | Engineered Structures
Revenue, Major Customer [Line Items]
Sales	0	0	0	0
Third-party sales | Commercial Transportation | Forged Wheels
Revenue, Major Customer [Line Items]
Sales	231	172	687	476
Third-party sales | Industrial and Other
Revenue, Major Customer [Line Items]
Sales	218	191	652	595
Third-party sales | Industrial and Other | Engine Products
Revenue, Major Customer [Line Items]
Sales	170	144	489	439
Third-party sales | Industrial and Other | Fastening Systems
Revenue, Major Customer [Line Items]
Sales	32	27	111	94
Third-party sales | Industrial and Other | Engineered Structures
Revenue, Major Customer [Line Items]
Sales	16	20	52	62
Third-party sales | Industrial and Other | Forged Wheels
Revenue, Major Customer [Line Items]
Sales	$ 0	$ 0	$ 0	$ 0