PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS - Assets Within Our Qualified and Registered Pension Plans (Details) (Qualified and Registered Pension Plans)	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	100.00%	100.00%
Fixed income
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	12.20%	11.40%
Hedge funds
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	60.60%	57.50%
Private equity and related funds
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	25.30%	28.60%
Real estate and related funds
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	1.40%	1.80%
Common and preferred stock and equity index instruments
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	0.70%	0.90%
Accrued liabilities
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	(0.20%)	(0.20%)