REGULATORY ASSETS AND LIABILITIES (Tables)

12 Months Ended

Dec. 31, 2012

Regulatory Assets and Liabilities Disclosure [Abstract]

Schedule of Regulatory Assets

Regulatory Assets consisted of the following items (in thousands):

	2012		2011
Environmental Remediation Costs:
Expended - Net	$	37,892	$	45,815
Liability for Future Expenditures	107,410		89,984
Deferred Asset Retirement Obligation Costs	30,199		25,162
Deferred Pension and Other Postretirement Benefit Costs	95,897		88,624
Deferred Gas Costs - Net	—		22,441
Conservation Incentive Program Receivable	31,686		13,580
Societal Benefit Costs Receivable	12,801		8,618
Premium for Early Retirement of Debt	1,075		537
Deferred Interest Rate Contracts	7,761		8,146
Energy Efficiency Tracker	12,306		8,464
Pipeline Supplier Service Charges	8,771		—
Other Regulatory Assets	6,858		3,850
Total Regulatory Assets	$	352,656	$	315,221

Schedule of Regulatory Liabilities

Regulatory Liabilities at December 31 consisted of the following items (in thousands):

	2012		2011
Excess Plant Removal Costs	$	45,593	$	47,230
Deferred Revenue - Net	10,924		—
Other Regulatory Liabilities	—		1,081
Total Regulatory Liabilities	$	56,517	$	48,311