Borrowings and Other Obligations (Narrative) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019	Dec. 12, 2019
Short-term Debt [Line Items]
Debt instrument, unused borrowing capacity, amount	$ 91
Short-term Borrowings and Current Portion of Long-term Debt	32	$ 13
Debt Instrument Covenant Debt Amount in Excess Default	75
A&R Credit Agreement Letters of Credit
Short-term Debt [Line Items]
Letters of credit outstanding, amount	123
LC Credit Agreement Letters of Credit
Short-term Debt [Line Items]
Letters of credit outstanding, amount	129
Other short-term bank loans
Short-term Debt [Line Items]
Short-term Borrowings and Current Portion of Long-term Debt	24	3
Committed Letters of Credit
Short-term Debt [Line Items]
Letters of credit outstanding, amount		$ 335
Letters of credit outstanding, cash collateral	72
Committed letters of credit
Short-term Debt [Line Items]
Letters of credit outstanding, amount	83
ABL Credit Agreement
Short-term Debt [Line Items]
Credit agreement, maximum capacity			$ 450
Other Borrowings	$ 20
LC Credit Agreement
Short-term Debt [Line Items]
Credit agreement, maximum capacity			$ 195
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