Employee Benefit Plans - PAC - Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Other Postretirement
Defined Benefit Plan Disclosure [Line Items]
Payment for settlement	$ 0	$ 0
Service cost	12	7	$ 8
Interest cost	19	21	27
Expected return on plan assets	(22)	(34)	(40)
Net amortization	(3)	(4)	(6)
Net periodic benefit cost (credit)	6	(10)	(11)
Other Postretirement | PAC
Defined Benefit Plan Disclosure [Line Items]
Payment for settlement	0	0
Service cost	2	2	2
Interest cost	7	9	12
Expected return on plan assets	(9)	(14)	(21)
Settlement	0	0	0
Net amortization	1	3	0
Net periodic benefit cost (credit)	1	0	(7)
United States | Pension
Defined Benefit Plan Disclosure [Line Items]
Payment for settlement	134	0
Service cost	30	17	16
Interest cost	78	93	111
Expected return on plan assets	(134)	(140)	(154)
Net amortization	25	32	31
Net periodic benefit cost (credit)	2	2	4
United States | Pension | PAC
Defined Benefit Plan Disclosure [Line Items]
Payment for settlement	52	0
Service cost	0	0	0
Interest cost	29	36	44
Expected return on plan assets	(51)	(56)	(67)
Settlement	6	0	0
Net amortization	21	18	11
Net periodic benefit cost (credit)	$ 5	$ (2)	$ (12)