Pension and Other Employee Benefits (Schedule of Change in Projected Benefit Obligation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Plan [Member]
Defined Benefit Plans and PRB Plans [Line Items]
PBO at beginning of year	$ 25,456	$ 28,569
Service cost	420	504	$ 473
Interest cost	1,046	1,004	1,088
Plan participants’ contributions	4	6
Amendments	1	10
Plan settlements	(7)	(474)
Actuarial loss (gain)	3,926	(1,580)
Foreign exchange loss (gain)	24	(56)
Benefits paid	(1,880)	(2,527)
PBO at end of year	28,990	25,456	28,569
PRB [Member]
Defined Benefit Plans and PRB Plans [Line Items]
PBO at beginning of year	672	745
Service cost	3	5	6
Interest cost	28	27	30
Plan participants’ contributions	58	49
Amendments	0	0
Plan settlements	(9)	(10)
Actuarial loss (gain)	71	(39)
Foreign exchange loss (gain)	0	0
Benefits paid	(112)	(105)
PBO at end of year	$ 711	$ 672	$ 745