v3.22.2.2
Accumulated Other Comprehensive Income​ (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2022
Sep. 30, 2021
Sep. 30, 2022
Sep. 30, 2021
AOCI Attributable to Parent [Abstract]        
Balance at beginning of period $ 1,808 $ 1,628 $ 1,559 $ 1,447
Other comprehensive income:        
Total Other comprehensive (loss) income, net of tax (34) 21 108 583
Balance at end of period 1,629 1,578 1,629 1,578
Restructuring and other charges (E) 112 14 119 612
Lease cost 13 15 40 45
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Restructuring and other charges (E) 112 14 119 612
2022 Restructuring Programs        
Other comprehensive income:        
Restructuring and other charges (E) 112   119  
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Restructuring and other charges (E) 112   119  
One-time Termination Benefits | 2022 Restructuring Programs        
Other comprehensive income:        
Restructuring and other charges (E)     1  
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Restructuring and other charges (E)     1  
Pension and other postretirement benefits        
AOCI Attributable to Parent [Abstract]        
Balance at beginning of period (1,037) (1,199) (1,121) (1,791)
Other comprehensive income:        
Other Comprehensive Income (Loss), before Reclassifications, before Tax 36 34 105 178
Other Comprehensive Income (Loss) before Reclassifications, Tax (8) (8) (23) (41)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax 28 26 82 137
Amortization of net actuarial loss and prior service cost 34 25 74 651
Tax expense (7) (6) (17) (151)
Total amount reclassified from Accumulated other comprehensive loss, net of tax 27 19 57 500
Total Other comprehensive (loss) income, net of tax 55 45 139 637
Balance at end of period (982) (1,154) (982) (1,154)
Foreign currency translation        
AOCI Attributable to Parent [Abstract]        
Balance at beginning of period (37) 35 25 29
Other comprehensive income:        
Total Other comprehensive (loss) income, net of tax (72) (11) (134) (5)
Balance at end of period (109) 24 (109) 24
Cash flow hedges        
AOCI Attributable to Parent [Abstract]        
Balance at beginning of period 105 (35) (15) 1
Other comprehensive income:        
Other Comprehensive Income (Loss), before Reclassifications, before Tax 78 (66) 136 (160)
Other Comprehensive Income (Loss) before Reclassifications, Tax (19) 15 (32) 37
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax 59 (51) 104 (123)
Amortization of net actuarial loss and prior service cost (100) 49 (1) 96
Tax expense 24 (11) 0 (22)
Total amount reclassified from Accumulated other comprehensive loss, net of tax (76) 38 (1) 74
Total Other comprehensive (loss) income, net of tax (17) (13) 103 (49)
Balance at end of period 88 (48) 88 (48)
Cash flow hedges | Aluminum Contract        
Other comprehensive income:        
Amortization of net actuarial loss and prior service cost 93 (50) (13) (98)
Cash flow hedges | Energy Related Derivative        
Other comprehensive income:        
Amortization of net actuarial loss and prior service cost 8 0 15 0
Cash flow hedges | Commodity Contract        
Other comprehensive income:        
Amortization of net actuarial loss and prior service cost (1) 1 (1) 2
Accumulated other comprehensive loss        
AOCI Attributable to Parent [Abstract]        
Balance at beginning of period (969) (1,199) (1,111) (1,761)
Other comprehensive income:        
Total Other comprehensive (loss) income, net of tax (34) 21 108 583
Balance at end of period $ (1,003) $ (1,178) $ (1,003) $ (1,178)