Employee Benefit Plans (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019
Components of Net Periodic Benefit Costs:
Defined benefit pension cost	$ 9,000,000	$ 21,000,000	$ 46,000,000	$ 89,000,000
Forecast
Contributions [Abstract]
Expected reduction in defined contribution plan expense					$ 25,000,000
Pension Plan
Contributions [Abstract]
Defined benefit plan, contributions by employer			97,000,000	107,000,000		$ 141,000,000
Defined benefit plan, expected future employer contributions	135,000,000		135,000,000
Pension Plan | U.S.
Components of Net Periodic Benefit Costs:
Service cost	0	1,000,000	1,000,000	2,000,000
Interest cost	21,000,000	25,000,000	65,000,000	83,000,000
Expected return on plan assets	(27,000,000)	(26,000,000)	(79,000,000)	(77,000,000)
Recognized net actuarial loss (gain)	6,000,000	7,000,000	20,000,000	18,000,000
Amortization of prior service credit	0	0	(1,000,000)	(1,000,000)
Recognized settlement loss	10,000,000	18,000,000	42,000,000	76,000,000
Recognized curtailment gain			0	0
Defined benefit pension cost	10,000,000	25,000,000	48,000,000	101,000,000
Defined contribution plans	(10,000,000)	6,000,000	1,000,000	19,000,000
Net Periodic Benefit Cost (Credit)	0	31,000,000	49,000,000	120,000,000
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss):
Net actuarial loss (gain)	77,000,000	135,000,000	(3,000,000)	171,000,000
Amortization of net actuarial (loss) gain	(16,000,000)	(25,000,000)	(62,000,000)	(94,000,000)
Amortization of net prior service credit	0	0	1,000,000	1,000,000
Total Recognized in Other Comprehensive Income (Loss)	61,000,000	110,000,000	(64,000,000)	78,000,000
Total Recognized in Net Periodic Benefit (Credit) Cost and Other Comprehensive Income (Loss)	61,000,000	141,000,000	(15,000,000)	198,000,000
Contributions [Abstract]
Defined benefit plan, contributions by employer			18,000,000	19,000,000		26,000,000
Defined benefit plan, expected future employer contributions	25,000,000		25,000,000
Pension Plan | U.S. | Qualified Plan
Contributions [Abstract]
Mandatory future contributions	0		0
Pension Plan | Non-U.S.
Components of Net Periodic Benefit Costs:
Service cost	5,000,000	5,000,000	15,000,000	17,000,000
Interest cost	29,000,000	37,000,000	84,000,000	114,000,000
Expected return on plan assets	(49,000,000)	(56,000,000)	(142,000,000)	(174,000,000)
Recognized net actuarial loss (gain)	15,000,000	10,000,000	43,000,000	32,000,000
Amortization of prior service credit	(1,000,000)	0	(1,000,000)	(1,000,000)
Recognized settlement loss	0	0	0	0
Recognized curtailment gain			(1,000,000)	0
Defined benefit pension cost	(1,000,000)	(4,000,000)	(2,000,000)	(12,000,000)
Defined contribution plans	6,000,000	5,000,000	16,000,000	17,000,000
Net Periodic Benefit Cost (Credit)	5,000,000	1,000,000	14,000,000	5,000,000
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss):
Net actuarial loss (gain)	0	0	0	0
Amortization of net actuarial (loss) gain	(15,000,000)	(10,000,000)	(43,000,000)	(32,000,000)
Amortization of net prior service credit	1,000,000	0	1,000,000	1,000,000
Total Recognized in Other Comprehensive Income (Loss)	(14,000,000)	(10,000,000)	(42,000,000)	(31,000,000)
Total Recognized in Net Periodic Benefit (Credit) Cost and Other Comprehensive Income (Loss)	(9,000,000)	(9,000,000)	(28,000,000)	(26,000,000)
Contributions [Abstract]
Defined benefit plan, contributions by employer			79,000,000	88,000,000		115,000,000
Defined benefit plan, expected future employer contributions	110,000,000		110,000,000
Retiree Health
Components of Net Periodic Benefit Costs:
Service cost	1,000,000	0	2,000,000	1,000,000
Interest cost	2,000,000	3,000,000	8,000,000	11,000,000
Expected return on plan assets	0	0	0	0
Recognized net actuarial loss (gain)	0	(1,000,000)	(1,000,000)	(3,000,000)
Amortization of prior service credit	(19,000,000)	(19,000,000)	(57,000,000)	(57,000,000)
Recognized settlement loss	0	0	0	0
Recognized curtailment gain			0	0
Defined benefit pension cost	(16,000,000)	(17,000,000)	(48,000,000)	(48,000,000)
Net Periodic Benefit Cost (Credit)	(16,000,000)	(17,000,000)	(48,000,000)	(48,000,000)
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss):
Net actuarial loss (gain)	0	(9,000,000)	(6,000,000)	(9,000,000)
Amortization of net actuarial (loss) gain	0	1,000,000	1,000,000	3,000,000
Amortization of net prior service credit	19,000,000	19,000,000	57,000,000	57,000,000
Total Recognized in Other Comprehensive Income (Loss)	19,000,000	11,000,000	52,000,000	51,000,000
Total Recognized in Net Periodic Benefit (Credit) Cost and Other Comprehensive Income (Loss)	3,000,000	$ (6,000,000)	4,000,000	3,000,000
Contributions [Abstract]
Defined benefit plan, contributions by employer			17,000,000	$ 22,000,000		$ 30,000,000
Defined benefit plan, expected future employer contributions	$ 30,000,000		$ 30,000,000