PENSION PLANS AND OTHER POST-RETIREMENT BENEFITS - Contributions (Details)	6 Months Ended
	Jun. 30, 2019 USD ($) item employee
Defined benefit plans
Number of non-contributory qualified defined benefit pension plans | item	3
New benefits accrued	$ 0
Defined Benefit Plans
Defined benefit plans
New benefits accrued	0
Expected contribution to pension plan	27,500,000
Employer contributions	$ 12,100,000
Post-retirement Benefit Obligations
Defined benefit plans
Number of persons eligible to become a new participant | employee	0
Assets in unfunded plans	$ 0
Expected contribution to pension plan	9,500,000
Employer contributions	$ 3,700,000
Supplemental Plans
Defined benefit plans
Number of non-qualified plans | item	2
Number of persons eligible to become a new participant | item	0
Assets in unfunded plans	$ 0