Special Charges - Components of Special Charges (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Other Income and Expenses [Abstract]
Impairment of assets	$ 50	$ 8
Severance and benefit costs	0	6
(Gains) losses on sale of assets and other special charges	13	4
Total operating special charges	63	18
Nonoperating credit loss on BRW Term Loan and related guarantee	697	0
Nonoperating unrealized (gains) losses on investments	319	(17)
Total special charges, credit losses and unrealized (gains) losses on investments, net	1,079	1
Income tax benefit, net of valuation allowance	(14)	0
Total special charges, credit losses and unrealized (gains) losses on investments, net of income taxes	$ 1,065	$ 1