Acquisitions - Summary of Components of Purchase Price Allocations (Details) - USD ($) $ in Millions	Dec. 31, 2021	Sep. 30, 2021	Sep. 01, 2021	Dec. 31, 2020
Liabilities assumed:
Goodwill	$ 3,748	$ 3,770		$ 3,564
Mountaineer
Assets acquired:
Cash and cash equivalents			$ 3
Accounts receivable			14
Inventories			41
Other current assets			21
Property, plant and equipment			397
Other noncurrent assets			48
Total assets acquired			524
Liabilities assumed:
Short-term borrowings			55
Accounts payable			20
Other current liabilities			52
Long-term debt			164
Pension and other postretirement benefit obligation			33
Deferred income taxes			21
Other noncurrent liabilities			29
Total liabilities assumed			374
Goodwill			250
Net consideration transferred			$ 400