Employee Benefit Plans (Schedule of Defined Benefit Plan Disclosures) (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Aug. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss (gain)	$ 425
Plan amendments		$ 2,100
Other	$ 180	(51)	$ (93)	$ 105
Fair value of plan assets		62,318	36,225
Noncurrent liability		(10,342)	(2,487)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligations		71,257	38,027	34,344
Service Cost		483	261	265
Interest cost		1,650	1,245	1,058
Actuarial loss (gain)		7,029	4,247
Total benefits paid(1)		(3,623)	(2,016)
Net settlement, curtailment, and special termination benefits		(4)	(206)
Plan amendments		(2,088)	0
Business combinations and divestitures(2)		29,385	(6)
Other		397	124
Fair value of plan assets		62,318	36,225	32,150
Actual return on plan assets		9,885	5,873
Employer contributions(1)		1,201	137
Total benefits paid(1)		(3,623)	(2,016)
Settlements		(32)	(17)
Business combinations and divestitures(2)		18,310	(10)
Other (3)		352	108
Funded status of plan		(8,939)	(1,802)
Noncurrent assets		424	19
Current liability		(232)	(51)
Noncurrent liability		(9,131)	(1,770)
Net amount recognized		(8,939)	(1,802)
Net actuarial (gain) loss		8,023	8,160
Prior service (credit) cost		(1,947)	190
Net amount recognized		6,076	9,113
Pension Plan [Member] | Continuing operations [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost		483	261
Pension Plan [Member] | Discontinued Operations [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost		1	34
Net amount recognized		0	763
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligations		1,535	765	810
Service Cost		6	2	2
Interest cost		37	31	26
Actuarial loss (gain)		114	(11)
Total benefits paid(1)		(144)	(69)
Net settlement, curtailment, and special termination benefits		(8)	0
Plan amendments		(7)	0
Business combinations and divestitures(2)		724	0
Other		48	2
Fair value of plan assets		381	20	$ 20
Actual return on plan assets		80	0
Employer contributions(1)		102	69
Total benefits paid(1)		(144)	(69)
Settlements		(8)	0
Business combinations and divestitures(2)		286	0
Other (3)		45	0
Funded status of plan		(1,154)	(745)
Noncurrent assets		0	0
Current liability		(82)	(47)
Noncurrent liability		(1,072)	(698)
Net amount recognized		(1,154)	(745)
Net actuarial (gain) loss		(117)	(181)
Prior service (credit) cost		(9)	(4)
Net amount recognized		(126)	(185)
Other Postretirement Benefits Plan [Member] | Continuing operations [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost		6	2
Other Postretirement Benefits Plan [Member] | Discontinued Operations [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost		0	0
Net amount recognized		$ 0	$ 0