EMPLOYEE BENEFITS - Narrative (Details) - USD ($)		12 Months Ended
	Sep. 07, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Years of service used in determining benefits		5 years
Net actuarial loss recorded in AOCI expected to be recognized during 2017		$ 17,000,000
401(k) Plan
Employer matching contribution, time of service required		1 year
Employer matching contribution percentage				100.00%		100.00%
Employer matching contribution, Percent of employees' pay				4.00%	5.00%	5.00%
Employer matching contribution, addition		2.00%
Employer contribution amount		$ 61,000,000	$ 55,000,000	$ 52,000,000
Qualified Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial losses		585,000,000
Employer contributions	$ 75,000,000	0	$ 75,000,000
Expected contribution		$ 0
Discount rate		3.67%	4.19%	4.64%
Non-Qualified Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial losses			$ 634,000,000
Employer contributions		$ 8,000,000	$ 8,000,000
Expected contribution		$ 8,000,000
Discount rate		3.53%	4.05%	4.54%
Postretirement Benefit Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Expected contribution		$ 2,000,000
Discount rate		3.20%	3.53%
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Assumed annual rate of increase in the per capita cost of covered health care benefits		7.00%	7.00%
Ultimate health care cost trend rate		5.00%	5.00%