v3.23.2
Accumulated Other Comprehensive Income​ (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2023
Jun. 30, 2022
Jun. 30, 2023
Jun. 30, 2022
AOCI Attributable to Parent [Abstract]        
Balance at beginning of period $ 1,397 $ 1,561 $ 1,357 $ 1,559
Other comprehensive income:        
Total Other comprehensive income, net of tax 28 161 38 142
Balance at end of period 1,484 1,808 1,484 1,808
Pension and other postretirement benefits        
AOCI Attributable to Parent [Abstract]        
Balance at beginning of period (888) (1,063) (892) (1,121)
Other comprehensive income:        
Other Comprehensive Income (Loss), before Reclassifications, before Tax (1) 14 (2) 69
Other Comprehensive Income (Loss) before Reclassifications, Tax 1 (3) 0 (15)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax 0 11 (2) 54
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax 10 20 20 40
Tax expense (2) (5) (6) (10)
Total amount reclassified from Accumulated other comprehensive loss, net of tax 8 15 14 30
Total Other comprehensive income, net of tax 8 26 12 84
Balance at end of period (880) (1,037) (880) (1,037)
Foreign currency translation        
AOCI Attributable to Parent [Abstract]        
Balance at beginning of period (34) 18 (51) 25
Other comprehensive income:        
Total Other comprehensive income, net of tax (13) (55) 4 (62)
Balance at end of period (47) (37) (47) (37)
Cash flow hedges        
AOCI Attributable to Parent [Abstract]        
Balance at beginning of period (5) (85) 6 (15)
Other comprehensive income:        
Other Comprehensive Income (Loss), before Reclassifications, before Tax 55 201 34 58
Other Comprehensive Income (Loss) before Reclassifications, Tax (13) (46) (8) (13)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax 42 155 26 45
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax (11) 46 (5) 99
Tax expense 2 (11) 1 (24)
Total amount reclassified from Accumulated other comprehensive loss, net of tax (9) 35 (4) 75
Total Other comprehensive income, net of tax 33 190 22 120
Balance at end of period 28 105 28 105
Cash flow hedges | Aluminum Contract        
Other comprehensive income:        
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax 18 (53) 17 (106)
Cash flow hedges | Energy Related Derivative        
Other comprehensive income:        
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax (6) 7 (11) 7
Cash flow hedges | Commodity Contract        
Other comprehensive income:        
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax (1) 0 (1) 0
Accumulated other comprehensive loss        
AOCI Attributable to Parent [Abstract]        
Balance at beginning of period (927) (1,130) (937) (1,111)
Other comprehensive income:        
Total Other comprehensive income, net of tax 28 161 38 142
Balance at end of period $ (899) $ (969) $ (899) $ (969)