Stockholders' Equity Stockholders' Equity Reclassifications from AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total cash flow hedges, energy commodity contract reclassifications	$ 331	$ 535	$ (375)
Provision (benefit) for income taxes	(138)	1,974	25
Net income (loss)	193	2,509	(350)
Net Income (Loss) Attributable to Noncontrolling Interest	(348)	$ (335)	$ (74)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	5
Accumulated Defined Benefit Plans Adjustment [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	35
Foreign currency translation [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	55
Provision (benefit) for income taxes	(12)
Net income (loss)	43
Net Income (Loss) Attributable to Noncontrolling Interest	(3)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	40
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of actuarial (gain) loss included in net periodic benefit cost	46
Reclassification out of Accumulated Other Comprehensive Income [Member] | Energy Commodity Contract [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Product sales	$ 9