Consolidated Balance Sheet (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Current Assets:
Cash	$ 164	$ 148
Receivables:
Trade less allowance of $407 ($406 in 2010)	107,585	96,699
Affiliates	5,903	4,921
Advances to affiliate	253,611	108,838
Other	14,004	13,735
Transportation and exchange gas receivables	4,914	2,417
Gas in storage, at LIFO	0	8,767
Gas in storage, at original cost	822	802
Gas available for customer nomination, at average cost	349	43,631
Material and supplies, at lower of average cost or market	34,437	32,225
Regulatory assets	37,877	48,444
Other	12,973	13,132
Total current assets	472,639	373,759
Investments, at cost plus equity in undistributed earnings	56,994	43,753
Property, Plant and Equipment:
Natural gas transmission plant	8,089,338	7,674,366
Less-Accumulated depreciation and amortization	2,801,104	2,650,133
Total property, plant and equipment, net	5,288,234	5,024,233
Other Assets:
Regulatory assets	207,945	198,921
Other	50,471	59,223
Total other assets	258,416	258,144
Total assets	6,076,283	5,699,889
Payables:
Trade	93,862	73,121
Affiliates	16,937	18,769
Cash overdrafts	14,844	19,526
Transportation and exchange gas payables	2,784	1,646
Property and other taxes	11,672	9,052
Interest	25,947	26,061
Regulatory liabilities	1,958	2,253
Customer advances	20,221	24,976
Asset retirement obligations	57,403	31,000
Other	23,189	25,783
Current maturities of long-term debt	324,321	299,932
Total current liabilities	593,138	532,119
Long-Term Debt	1,029,397	980,018
Other Long-Term Liabilities:
Asset retirement obligations	245,365	220,644
Regulatory liabilities	182,848	115,563
Other	6,182	6,785
Total other long-term liabilities	434,395	342,992
Contingent liabilities and commitments (Note 2)
Owner's Equity:
Member's capital	1,841,888	1,727,434
Loans to parent	0	0
Retained earnings	2,177,811	2,117,153
Accumulated other comprehensive income (loss)	(346)	173
Total owner's equity	4,019,353	3,844,760
Total liabilities and owner's equity	$ 6,076,283	$ 5,699,889