Statement of Consolidated Cash Flows (unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Operating activities
Net income	$ 36	$ 95	$ 155	$ 161
Adjustments to reconcile net income to cash used for operations:
Depreciation and amortization			271	407
Deferred income taxes			25	(36)
Restructuring and other charges			148	630
Net loss from investing activities—asset sales			6	6
Net periodic pension benefit cost (G)			42	87
Stock-based compensation			35	44
Other			63	15
Changes in assets and liabilities, excluding effects of acquisitions, divestitures, and foreign currency translation adjustments:
(Increase) in receivables			(117)	(957)
(Increase) in inventories			(42)	(92)
Decrease in prepaid expenses and other current assets			1	17
(Decrease) in accounts payable, trade (A)			(439)	(2)
(Decrease) in accrued expenses			(177)	(90)
Increase in taxes, including income taxes			41	92
Pension contributions			(110)	(217)
(Increase) in noncurrent assets			(5)	(12)
(Decrease) in noncurrent liabilities			(39)	(36)
Cash (used for) provided by operations			(142)	17
Financing Activities
Net change in short-term borrowings (original maturities of three months or less)			(8)	0
Additions to debt (original maturities greater than three months) (B)(O)			2,400	300
Payments on debt (original maturities greater than three months) (O)			(2,041)	(303)
Debt issuance costs (B)(O)			(61)	0
Premiums paid on early redemption of debt (O)			(59)	0
Proceeds from exercise of employee stock options			30	19
Dividends paid to shareholders			(10)	(48)
Repurchase of common stock			(51)	(1,100)
Net cash transferred to Arconic Corporation at separation (B)			(500)	0
Other			(39)	(12)
Cash used for financing activities			(339)	(1,144)
Investing Activities
Capital expenditures (A)(D)	(36)	(127)	(220)	(532)
Proceeds from the sale of assets and businesses (B)(Q)			114	27
Sale of debt securities			0	47
Cash receipts from sold receivables (K)			258	630
Other			0	(1)
Cash provided from investing activities			152	171
Effect of exchange rate changes on cash, cash equivalents and restricted cash			(6)	(2)
Net change in cash, cash equivalents and restricted cash			(335)	(958)
Cash, cash equivalents and restricted cash at beginning of period			1,703	2,282	$ 2,282
Cash, cash equivalents and restricted cash at end of period	$ 1,368	$ 1,324	$ 1,368	$ 1,324	$ 1,703