EMPLOYEE BENEFIT PLANS (Additional Information) (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) plans	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Number of defined benefit pension plans | plans	3
number of qualified defined benefit pension plans | plans	2
Approximate percentage of net periodic benefit cost that was capitalized	19.00%	19.00%	19.00%
Investment Return Model Best-Estimate Range	20 years
Matching 401(k) contributions made	$ 5,000,000	$ 5,000,000	$ 5,000,000
Level 3 [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value measurements of plan assets	26,000,000	25,000,000	23,000,000
Pension Plan [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation	384,000,000	355,000,000
Fair value measurements of plan assets	354,000,000	336,000,000	335,000,000
Pension Plan [Member] | Level 3 [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value measurements of plan assets	$ 26,000,000	25,000,000
Index value percentage of real estate assets	100.00%
Transfers between levels	$ 0	0
Other Postretirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Employer Contribution to VEBA Trust	2,000,000	4,000,000	3,000,000
Fair value measurements of plan assets	14,000,000	13,000,000	$ 12,000,000
Other Postretirement Benefits [Member] | FairValueInputsLevel1AndLevel2 [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value measurements of plan assets	14,000,000	13,000,000
Other Postretirement Benefits [Member] | Level 3 [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value measurements of plan assets	$ 0	0
Minimum [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Percentile of investment return model range used	25.00%
Maximum [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Percentile of investment return model range used	75.00%
Fixed Income | Pension Plan [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value measurements of plan assets	$ 144,000,000	137,000,000
Fixed Income | Pension Plan [Member] | Level 3 [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value measurements of plan assets	0	0
Fixed Income | Other Postretirement Benefits [Member] | FairValueInputsLevel1AndLevel2 [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value measurements of plan assets	5,000,000	5,000,000
Equities | Other Postretirement Benefits [Member] | FairValueInputsLevel1AndLevel2 [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value measurements of plan assets	$ 9,000,000	$ 8,000,000