Transactions with Related Parties - Additional Information (Detail) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | |||
---|---|---|---|---|---|
Sep. 30, 2019 |
Sep. 30, 2018 |
Sep. 30, 2019 |
Sep. 30, 2018 |
Dec. 31, 2018 |
|
Related Party Transaction [Line Items] | |||||
Net sales to related parties | $ 367 | $ 378 | $ 1,112 | $ 1,072 | |
Accounts payable to related parties | 111 | 111 | $ 81 | ||
Outside processing services | |||||
Related Party Transaction [Line Items] | |||||
Purchases from related parties | 7 | 8 | 23 | 23 | |
Taconite pellets | |||||
Related Party Transaction [Line Items] | |||||
Purchases from related parties | 27 | $ 23 | 78 | $ 66 | |
PRO-TEC Coating Company | |||||
Related Party Transaction [Line Items] | |||||
Accounts payable to related parties | 109 | 109 | 80 | ||
Other equity investees | |||||
Related Party Transaction [Line Items] | |||||
Accounts payable to related parties | $ 2 | $ 2 | $ 1 |