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, 2021	Dec. 31, 2020
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	$ 830	$ 487
Relating to assets still held at the reporting date	10	31
Defined Benefit Plan Purchases	26	58
Settlements	(71)	(45)
Transfers into (out of) Level 3	8	299
Fair value of net plan assets as of the end of year	803	830
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	594	245
Relating to assets still held at the reporting date	(21)	19
Defined Benefit Plan Purchases	17	34
Settlements	(20)	(3)
Transfers into (out of) Level 3	7	299
Fair value of net plan assets as of the end of year	577	594
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	5
Relating to assets still held at the reporting date	0	(3)
Defined Benefit Plan Purchases	0	0
Settlements	0	0
Transfers into (out of) Level 3	1	0
Fair value of net plan assets as of the end of year	3	2
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	234	237
Relating to assets still held at the reporting date	31	15
Defined Benefit Plan Purchases	9	24
Settlements	(51)	(42)
Transfers into (out of) Level 3	0	0
Fair value of net plan assets as of the end of year	$ 223	$ 234