Employee Benefits - Net Postretirement Benefit Cost and the Amount Recognized in OCI for All Funded and Unfunded Plans (Details) - Other Postretirement Benefit Plans - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Service cost of benefits earned	$ 0	$ 0	$ 1
Interest cost on APBO	2	2	2
Expected return on plan assets	(2)	(2)	(2)
Amortization of prior service credit	(1)	(1)	0
Amortization of gains	(1)	0	(1)
Net pension cost (benefit)	(2)	(1)	0
Other changes in plan assets and benefit obligations recognized in OCI:
Net (gain) loss	1	1	1
Amortization of prior service credit	1	0	1
Amortization of losses	0	0	0
Total recognized in comprehensive income	2	1	2
Total recognized in net postretirement benefit cost and comprehensive income	$ 0	$ 0	$ 2