Employee Benefits - Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Components of net periodic cost for retirement plans and post-retirement plans
Settlement charge	$ (3)	$ (3)	$ (113)
Other changes in plan assets and benefit obligations recognized in other comprehensive income, net of tax
Settlement charge			113
Total recognized	(23)	23	(102)
Non-Cash settlement charge of unamortized actuarial loss, before tax	3	3
Retirement Plans
Components of net periodic cost for retirement plans and post-retirement plans
Service cost	4	4	3
Interest cost	40	52	64
Expected return on assets	(104)	(102)	(108)
Actuarial loss (gain)	21	17	12
Prior service credit	0	0	0
Net periodic benefit cost	(39)	(29)	(29)
Settlement charge	3	3	113
Net periodic benefit cost	(36)	(26)	84
Other changes in plan assets and benefit obligations recognized in other comprehensive income, net of tax
Net actuarial loss (gain)	(6)	28	(10)
Recognized actuarial (gain) loss	(15)	(9)	(10)
Prior service cost	0	0	0
Settlement charge	(2)	(2)	(85)
Total recognized	(23)	17	(105)
Postretirement Plans
Components of net periodic cost for retirement plans and post-retirement plans
Service cost	0	0	0
Interest cost	1	1	1
Expected return on assets	0	0	0
Actuarial loss (gain)	(2)	(2)	(2)
Prior service credit	(1)	(1)	(1)
Net periodic benefit cost	(2)	(2)	(2)
Settlement charge	0	0	0
Net periodic benefit cost	(2)	(2)	(2)
Other changes in plan assets and benefit obligations recognized in other comprehensive income, net of tax
Net actuarial loss (gain)	(1)	1	0
Recognized actuarial (gain) loss	1	2	1
Prior service cost	(1)	1	1
Settlement charge	0	0	0
Total recognized	$ (1)	$ 4	$ 2