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Employee Benefit Plans - Change in Benefit Obligation and Plan Assets (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]      
Fair value of plan assets at beginning of year $ 406.9    
Fair value of plan assets at end of year 408.1 $ 406.9  
Pension Plan [Member]      
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]      
Benefit obligation at beginning of year 482.4 674.1  
Service cost 1.1 1.7 $ 2.0
Interest cost 24.4 16.5 17.3
Plan amendments (0.6) 0.0  
Actuarial loss (gain) 6.7 (175.9)  
Change in GM portion of OPEB obligation 0.0 0.0  
Participant contributions 0.2 0.2  
Curtailments (0.5) 0.0  
Settlements (6.1) 0.0  
Benefit payments (27.5) (27.4)  
Tekfor acquisition 0.0 14.3  
Currency fluctuations 6.8 (21.1)  
Net change 4.5 (191.7)  
Benefit obligation at end of year 486.9 482.4 674.1
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]      
Fair value of plan assets at beginning of year 406.9 573.8  
Actual return on plan assets 19.0 (127.1)  
Employer contributions 9.2 2.5  
Participant contributions 0.2 0.2  
Benefit payments (27.5) (27.4)  
Settlements (6.1) 0.0  
Tekfor acquisition 0.0 7.5  
Currency fluctuations 6.4 (22.6)  
Net change 1.2 (166.9)  
Fair value of plan assets at end of year 408.1 406.9 573.8
Other Postretirement Benefits Plan [Member]      
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]      
Benefit obligation at beginning of year 329.6 509.6  
Service cost 0.2 0.3 0.3
Interest cost 10.1 8.4 8.4
Plan amendments 0.0 (0.5)  
Actuarial loss (gain) (21.4) (101.3)  
Change in GM portion of OPEB obligation (18.2) (75.0)  
Participant contributions 0.0 0.0  
Curtailments 0.0 0.0  
Settlements 0.0 0.0  
Benefit payments (12.5) (11.9)  
Tekfor acquisition 0.0 0.0  
Currency fluctuations 0.0 0.0  
Net change (41.8) (180.0)  
Benefit obligation at end of year 287.8 329.6 509.6
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]      
Fair value of plan assets at beginning of year 0.0 0.0  
Actual return on plan assets 0.0 0.0  
Employer contributions 12.5 11.9  
Participant contributions 0.0 0.0  
Benefit payments (12.5) (11.9)  
Settlements 0.0 0.0  
Tekfor acquisition 0.0 0.0  
Currency fluctuations 0.0 0.0  
Net change 0.0 0.0  
Fair value of plan assets at end of year $ 0.0 $ 0.0 $ 0.0