Retirement Benefits - Reconciliation of Level 3 Assets and Liabilities measured at Fair Value for Pension and Other Postretirement Benefit Plans (Details) - Pension and other post retirement benefit [Member] - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of net plan assets as of the beginning of year	$ 469	$ 485
Relating to assets still held at the reporting date	(24)	6
Relating to assets sold during the period	(6)
Defined Benefit Plan Purchases	7	15
Settlements	(53)	(42)
Transfers into (out of) Level 3	(381)	5
Fair value of net plan assets as of the end of year	12	469
Debt Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of net plan assets as of the beginning of year	337	348
Relating to assets still held at the reporting date	(9)	(12)
Relating to assets sold during the period	(19)
Defined Benefit Plan Purchases	0	10
Settlements	(1)	(13)
Transfers into (out of) Level 3	(296)	4
Fair value of net plan assets as of the end of year	12	337
Equity Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of net plan assets as of the beginning of year	2	1
Relating to assets still held at the reporting date	0	0
Defined Benefit Plan Purchases	0	0
Settlements	0	0
Transfers into (out of) Level 3	(2)	1
Fair value of net plan assets as of the end of year	0	2
Equity Security Individually Held [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Relating to assets sold during the period	0
Private Placement [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of net plan assets as of the beginning of year	130	136
Relating to assets still held at the reporting date	(15)	18
Relating to assets sold during the period	13
Defined Benefit Plan Purchases	7	5
Settlements	(52)	(29)
Transfers into (out of) Level 3	(83)	0
Fair value of net plan assets as of the end of year	$ 0	$ 130