Other Operating Expenses, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Operating Expenses, Net [Abstract]
Merger and restructuring costs	$ 10	$ 97	$ 351
Special charges, net	51	53	(21)
Loss on sale of assets, net	42	85	16
Other operating expenses, net	103	235	346
Merger and Restructuring Costs [Roll Forward]
Accrued merger and restructuring costs, beginning of period	75	198	276
Costs incurred	10	92	302
Cash paid	(68)	(215)	(380)
Accrued merger and restructuring costs, end of period	17	75	198
Stock compensation expense recognized in merger costs		5	49
Obligation charge arising from a withdrawal liability from a multi-employer pension plan		22	83
Benefit arising from remeasurement of a liability as a result of tax reform			101
Impairment Charge	42	75
Employee Retention Costs
Merger and Restructuring Costs [Roll Forward]
Accrued merger and restructuring costs, beginning of period	1	1	7
Costs incurred	0	1	4
Cash paid	(1)	(1)	(10)
Accrued merger and restructuring costs, end of period	0	1	1
Employee Termination Costs
Merger and Restructuring Costs [Roll Forward]
Accrued merger and restructuring costs, beginning of period	57	172	244
Costs incurred	1	64	226
Cash paid	(51)	(179)	(298)
Accrued merger and restructuring costs, end of period	7	57	172
Transaction and Advisory Costs
Merger and Restructuring Costs [Roll Forward]
Accrued merger and restructuring costs, beginning of period	11	17	25
Costs incurred	8	2	4
Cash paid	(12)	(8)	(12)
Accrued merger and restructuring costs, end of period	7	11	17
Other Costs
Merger and Restructuring Costs [Roll Forward]
Accrued merger and restructuring costs, beginning of period	6	8	0
Costs incurred	1	25	68
Cash paid	(4)	(27)	(60)
Accrued merger and restructuring costs, end of period	$ 3	$ 6	$ 8