PENSION AND OTHER POSTRETIREMENT BENEFITS - FUTURE BENEFIT PAYMENTS (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]
Contributions to qualified employee pension plans	$ 0	$ 12,020,000	$ 0
Pension Benefits
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2017	10,339,000
2018	10,619,000
2019	11,472,000
2020	11,921,000
2021	12,481,000
2022- 2026	73,847,000
Contributions to qualified employee pension plans	12,000,000	0
Employer Contributions	2,244,000	14,002,000
Other Postretirement Benefits
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2017	3,600,000
2018	3,577,000
2019	3,677,000
2020	3,790,000
2021	3,811,000
2022- 2026	18,131,000
Employer Contributions	2,946,000	6,144,000
Estimated future contributions	3,600,000
Supplemental Employee Retirement Plans
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
Employer Contributions	2,300,000	$ 2,000,000	$ 1,500,000
Estimated future contributions	$ 2,400,000