Segment Information - Disaggregation of Revenue by Major End Market Served (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue, Major Customer [Line Items]
Sales	$ 1,195	$ 1,253	$ 2,404	$ 2,887
Third-party sales
Revenue, Major Customer [Line Items]
Sales	1,195	1,253	2,404	2,885
Third-party sales | Engine Products
Revenue, Major Customer [Line Items]
Sales	544	585	1,078	1,366
Third-party sales | Fastening Systems
Revenue, Major Customer [Line Items]
Sales	262	326	534	711
Third-party sales | Engineered Structures
Revenue, Major Customer [Line Items]
Sales	160	229	336	504
Third-party sales | Forged Wheels
Revenue, Major Customer [Line Items]
Sales	229	113	456	304
Third-party sales | Aerospace - Commercial
Revenue, Major Customer [Line Items]
Sales	468	680	923	1,628
Third-party sales | Aerospace - Commercial | Engine Products
Revenue, Major Customer [Line Items]
Sales	260	312	487	819
Third-party sales | Aerospace - Commercial | Fastening Systems
Revenue, Major Customer [Line Items]
Sales	129	224	277	481
Third-party sales | Aerospace - Commercial | Engineered Structures
Revenue, Major Customer [Line Items]
Sales	79	144	159	328
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	226	228	496	469
Third-party sales | Aerospace - Defense | Engine Products
Revenue, Major Customer [Line Items]
Sales	121	125	272	252
Third-party sales | Aerospace - Defense | Fastening Systems
Revenue, Major Customer [Line Items]
Sales	41	39	83	83
Third-party sales | Aerospace - Defense | Engineered Structures
Revenue, Major Customer [Line Items]
Sales	64	64	141	134
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	278	147	551	384
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	49	34	95	80
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	229	113	456	304
Third-party sales | Industrial and Other
Revenue, Major Customer [Line Items]
Sales	223	198	434	404
Third-party sales | Industrial and Other | Engine Products
Revenue, Major Customer [Line Items]
Sales	163	148	319	295
Third-party sales | Industrial and Other | Fastening Systems
Revenue, Major Customer [Line Items]
Sales	43	29	79	67
Third-party sales | Industrial and Other | Engineered Structures
Revenue, Major Customer [Line Items]
Sales	17	21	36	42
Third-party sales | Industrial and Other | Forged Wheels
Revenue, Major Customer [Line Items]
Sales	$ 0	$ 0	$ 0	$ 0