Pension and Other Employee Benefits (Schedule of Components of Net Periodic Benefit Expense (Income) Pension) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Non-operating expense
Loss recognized due to settlements	$ 288
Total non-service expense		$ 688	$ 1,230	$ 913
Pension Plan [Member]
Operating expense
Service cost		420	504	473
Non-operating expense
Interest cost		1,046	1,004	1,088
Expected return on plan assets		(1,436)	(1,435)	(1,377)
Amortization of prior service cost		5	6	5
Amortization of net actuarial loss		1,050	1,351	1,177
Loss recognized due to settlements		1	286	1
Total non-service expense		666	1,212	894
Net periodic expense (income)		$ 1,086	$ 1,716	$ 1,367