PENSION AND OTHER POSTRETIREMENT BENEFITS - CONTRIBUTIONS (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
Pension contribution	$ 0	$ 15,000,000	$ 0
Pension Benefits
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2017	12,141,000
2018	12,583,000
2019	13,529,000
2020	14,056,000
2021	14,757,000
2022- 2025	86,727,000
Pension contribution	0	15,000,000	0
Employer contributions	2,278,000	17,017,000
Other Postretirement Benefits
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2017	4,399,000
2018	4,316,000
2019	4,403,000
2020	4,514,000
2021	4,511,000
2022- 2025	21,308,000
Employer contributions	3,656,000	8,721,000
Expected contribution to plan	3,600,000
Supplemental Employee Retirement Plan
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
Employer contributions	2,300,000	$ 2,000,000	$ 1,500,000
Expected contribution to plan	$ 2,500,000