Employee Benefits - Pre-tax AOCI Not Yet Recognized as Net Postretirement Benefit Cost (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Total unrecognized AOCI	$ 381	$ 427
Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Net unrecognized losses (gains)	(9)	(10)
Net unrecognized prior service credit	(14)	(15)
Total unrecognized AOCI	$ (23)	$ (25)

Amount, before tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

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Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

+ References

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-Publisher FASB
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-Topic 715
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Amount, before tax, of accumulated other comprehensive (income) loss for cost (credit) of benefit change attributable to participants' prior service from plan amendment or plan initiation of defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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