EMPLOYEE BENEFITS - Schedule of Net Periodic (Income) Cost (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 3	$ 3	$ 3
Interest cost		43	46	48
Expected return on plan assets		(79)	(69)	(68)
Amortization of actuarial loss		17	18	16
Net periodic pension (income) cost	[1]	(16)	(2)	(1)
Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost		3	3	3
Interest cost		39	42	44
Expected return on plan assets		(79)	(69)	(68)
Amortization of actuarial loss		15	16	14
Net periodic pension (income) cost	[1]	(22)	(8)	(7)
Non-Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost		0	0	0
Interest cost		4	4	4
Expected return on plan assets		0	0	0
Amortization of actuarial loss		2	2	2
Net periodic pension (income) cost	[1]	$ 6	$ 6	$ 6

[1] In the Consolidated Statements of Operations, service cost is presented in salaries and employee benefits, and all other components of net periodic pension (income) costs are presented in other operating expense.