Employee Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 51	$ 60		$ 102	$ 120
Interest cost	47	46		94	92
Expected return on plan assets	(76)	(71)		(154)	(142)
Amortization of unrecognized (gain) loss	31	42		61	85
Amortization of prior service credit	0	0		0	0
Special termination benefits				0	0
Other	0	1		1	1
Total	53	78		104	156
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	3		4	5
Interest cost	8	7		15	13
Expected return on plan assets	(1)	(1)		(1)	(1)
Amortization of unrecognized (gain) loss	(4)	(7)		(7)	(14)
Amortization of prior service credit	(28)	(31)		(56)	(62)
Special termination benefits			$ 46	0	46
Other	0	0		0	0
Total	$ (23)	$ (29)		$ (45)	$ (13)