Fair Value Measurements - Assets and Liabilities at Fair Value, Nonrecurring (Details) - Nonrecurring Basis $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Properties, plant and equipment, net (held and used)	$ 2,171	$ 2,171
Properties, plant and equipment, net (held for sale)	655	655
Investments and advances	12	12
Total Assets at Fair Value	2,838	2,838
Properties, plant and equipment, net (held and used), Before-Tax Loss	2,551	2,551
Properties, plant and equipment, net (held for sale), Before-Tax Loss	92	166
Investments and advances, Before-Tax Loss	2,549	2,549
Total Assets at Fair Value, Before-Tax Loss	5,192	5,266
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Properties, plant and equipment, net (held and used)	0	0
Properties, plant and equipment, net (held for sale)	0	0
Investments and advances	0	0
Total Assets at Fair Value	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Properties, plant and equipment, net (held and used)	20	20
Properties, plant and equipment, net (held for sale)	655	655
Investments and advances	0	0
Total Assets at Fair Value	675	675
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Properties, plant and equipment, net (held and used)	2,151	2,151
Properties, plant and equipment, net (held for sale)	0	0
Investments and advances	12	12
Total Assets at Fair Value	$ 2,163	$ 2,163