Segment Information - Disaggregation of Revenue by Major End Market Served (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenue, Major Customer [Line Items]
Sales	$ 1,209	$ 1,634
Third-party sales
Revenue, Major Customer [Line Items]
Sales	1,209	1,632
Third-party sales | Engine Products
Revenue, Major Customer [Line Items]
Sales	534	781
Third-party sales | Fastening Systems
Revenue, Major Customer [Line Items]
Sales	272	385
Third-party sales | Engineered Structures
Revenue, Major Customer [Line Items]
Sales	176	275
Third-party sales | Forged Wheels
Revenue, Major Customer [Line Items]
Sales	227	191
Third-party sales | Aerospace - Commercial
Revenue, Major Customer [Line Items]
Sales	455	948
Third-party sales | Aerospace - Commercial | Engine Products
Revenue, Major Customer [Line Items]
Sales	227	507
Third-party sales | Aerospace - Commercial | Fastening Systems
Revenue, Major Customer [Line Items]
Sales	148	257
Third-party sales | Aerospace - Commercial | Engineered Structures
Revenue, Major Customer [Line Items]
Sales	80	184
Third-party sales | Aerospace - Commercial | Forged Wheels
Revenue, Major Customer [Line Items]
Sales	0	0
Third-party sales | Aerospace - Defense
Revenue, Major Customer [Line Items]
Sales	270	241
Third-party sales | Aerospace - Defense | Engine Products
Revenue, Major Customer [Line Items]
Sales	151	127
Third-party sales | Aerospace - Defense | Fastening Systems
Revenue, Major Customer [Line Items]
Sales	42	44
Third-party sales | Aerospace - Defense | Engineered Structures
Revenue, Major Customer [Line Items]
Sales	77	70
Third-party sales | Aerospace - Defense | Forged Wheels
Revenue, Major Customer [Line Items]
Sales	0	0
Third-party sales | Commercial Transportation
Revenue, Major Customer [Line Items]
Sales	273	237
Third-party sales | Commercial Transportation | Engine Products
Revenue, Major Customer [Line Items]
Sales	0	0
Third-party sales | Commercial Transportation | Fastening Systems
Revenue, Major Customer [Line Items]
Sales	46	46
Third-party sales | Commercial Transportation | Engineered Structures
Revenue, Major Customer [Line Items]
Sales	0	0
Third-party sales | Commercial Transportation | Forged Wheels
Revenue, Major Customer [Line Items]
Sales	227	191
Third-party sales | Industrial and Other
Revenue, Major Customer [Line Items]
Sales	211	206
Third-party sales | Industrial and Other | Engine Products
Revenue, Major Customer [Line Items]
Sales	156	147
Third-party sales | Industrial and Other | Fastening Systems
Revenue, Major Customer [Line Items]
Sales	36	38
Third-party sales | Industrial and Other | Engineered Structures
Revenue, Major Customer [Line Items]
Sales	19	21
Third-party sales | Industrial and Other | Forged Wheels
Revenue, Major Customer [Line Items]
Sales	$ 0	$ 0