Regulatory Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2012

Regulatory Assets and Liabilities Disclosure [Abstract]

Schedule of Regulatory Assets And Liabilities

We have specific orders to cover approximately 98% of our regulatory assets and 92% of our regulatory liabilities.

	Note Reference	Remaining Amortization Period	December 31,
			2012		2011
			(in thousands)
Pension	15	Undetermined	$	143,672	$	128,844
Employee related benefits	15	Undetermined	20,911		21,527
Competitive transition charges		1 Year	—		1,380
Distribution infrastructure projects		5 Years	15,679		4,883
Environmental clean-up	19	Various	16,497		16,998
Supply costs		1 Year	11,788		11,168
Energy supply derivatives	8	1 Year	5,428		20,312
Income taxes	12	Plant Lives	162,154		124,967
Deferred financing costs		1-13 Years	13,944		15,413
Other	—	Various	18,118		12,212
Total regulatory assets			$	408,191	$	357,704
Removal cost	6	Various	$	264,486	$	251,262
Gas storage sales		27 Years	11,251		11,672
Supply costs		1 Year	17,591		18,214
Deferred revenue	3	1 Year	26,259		10,984
Environmental clean-up		1 Year	1,395		1,645
State & local taxes & fees		1 Year	537		2,528
Other		Various	3,524		2,866
Total regulatory liabilities			$	325,043	$	299,171