Borrowings and Other Obligations (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2020	Aug. 27, 2020	Aug. 04, 2020	Dec. 31, 2019	Dec. 12, 2019
Short-term Debt [Line Items]
Debt instrument, unused borrowing capacity, amount	$ 47
Short-term Borrowings and Current Portion of Long-term Debt	14			$ 13
Debt Instrument Covenant Debt Amount in Excess Default	175	$ 200
Write off of Deferred Debt Issuance Cost	15
Debt Issuance Costs, Gross	25
Debt Related Commitment Fees and Debt Issuance Costs	15
LC Credit Agreement Letters of Credit
Short-term Debt [Line Items]
Letters of credit outstanding, amount	168
Other short-term bank loans
Short-term Debt [Line Items]
Short-term Borrowings and Current Portion of Long-term Debt	5			3
Committed Letters of Credit
Short-term Debt [Line Items]
Letters of credit outstanding, amount				$ 346
Letters of credit outstanding, cash collateral	170
Committed letters of credit
Short-term Debt [Line Items]
Letters of credit outstanding, amount	178
ABL Credit Agreement
Short-term Debt [Line Items]
Credit agreement, maximum capacity					$ 450
LC Credit Agreement
Short-term Debt [Line Items]
Credit agreement, maximum capacity					195
Deferred Finance Costs, Own-share Lending Arrangement, Issuance Costs, Gross	12
Deferred Finance Costs, Own-share Lending Arrangement, Issuance Costs, Accumulated Amortization Adjustment	$ 6
Amended LC Credit Agreement [Member]
Short-term Debt [Line Items]
Credit agreement, maximum capacity					$ 215
Senior Notes | Senior Notes 8.75 Percent Due 2024
Short-term Debt [Line Items]
Stated interest rate on debt			8.75%
Face amount of debt			$ 500
Senior Notes | Exit Notes, 11.00 Percent Due 2024
Short-term Debt [Line Items]
Stated interest rate on debt					11.00%
Face amount of debt					$ 2,100