Fair Value Measurements - Assets and Liabilities at Fair Value, Nonrecurring (Details) - Nonrecurring Basis $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)
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)	22	22
Investments and advances	0	0
Total Assets at Fair Value	22	22
Properties, plant and equipment, net (held and used), Before-Tax Loss	0	2,551
Properties, plant and equipment, net (held for sale), Before-Tax Loss	17	183
Investments and advances, Before-Tax Loss	0	2,550
Total Assets at Fair Value, Before-Tax Loss	17	5,284
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)	0	0
Properties, plant and equipment, net (held for sale)	22	22
Investments and advances	0	0
Total Assets at Fair Value	22	22
Level 3
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