RETIREMENT BENEFITS Retirement Benefits - Obligations and Funded Status (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan, Service Cost		$ 1	$ 0	$ 0
Interest cost		2	1	1
Fair value of plan assets at beginning of period		143
Fair value of plan assets at end of period		141	143
Other Postretirement Benefits Plan [Member]
Benefit obligation at beginning of period		25	19
Defined Benefit Plan, Service Cost		1	0
Interest cost		2	1
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment		56	8
Actuarial gain		(3)	(1)
Benefit obligation at end of period		78	25	19
Fair value of plan assets at beginning of period		143	126
Return on plan assets and other		(7)	11
Employer contributions		8	8
Defined Benefit Plan, Benefit Obligation, Benefits Paid		3	2
Fair value of plan assets at end of period		141	143	$ 126
Amount overfunded at end of period (1)	[1]	63	118
Net actuarial gain		(2)	(13)
Prior service cost		61	20
Amounts recognized in accumulated other comprehensive income (pre-tax basis) consist of:		$ 59	$ 7

[1] Recorded as a non-current asset in the consolidated balance sheets.