RETIREMENT BENEFITS Retirement Benefits - Obligations and Funded Status (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan, Service Cost		$ 1	$ 1	$ 1
Interest cost		2	3	3
Fair value of plan assets at beginning of period		191
Fair value of plan assets at end of period		218	191
Other Postretirement Benefits Plan [Member]
Benefit obligation at beginning of period		98	91
Defined Benefit Plan, Service Cost		1	1
Interest cost		2	3
Actuarial loss		1	7
Benefit obligation at end of period		98	98	91
Fair value of plan assets at beginning of period		191	169
Return on plan assets and other		23	18
Employer contributions		8	8
Defined Benefit Plan, Benefit Obligation, Benefits Paid		4	4
Fair value of plan assets at end of period		218	191	$ 169
Amount overfunded at end of period (1)	[1]	120	93
Net actuarial gain		(21)	(8)
Prior service cost		18	19
Amounts recognized in accumulated other comprehensive income (pre-tax basis) consist of:		$ (3)	$ 11

[1] Recorded as a non-current asset in the consolidated balance sheets with a non-current pension liability for overfunded amounts owed to the Company’s shippers.