PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS - Assets Within Our Qualified and Registered Pension Plans (Details)	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	100.00%	100.00%
Qualified and Registered Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	100.00%	100.00%
Qualified and Registered Pension Plans | Fixed income
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	11.40%	11.50%
Qualified and Registered Pension Plans | Hedge funds
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	55.30%	51.90%
Qualified and Registered Pension Plans | Private equity and related funds
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	31.80%	35.10%
Qualified and Registered Pension Plans | Real estate and related funds
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	1.80%	2.10%
Qualified and Registered Pension Plans | Common and preferred stock and equity index instruments
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	0.10%	0.00%
Qualified and Registered Pension Plans | Accrued liabilities
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	(0.40%)	(0.60%)