Condensed Consolidated Balance Sheet (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Current Assets:
Cash	$ 107	$ 185
Receivables:
Affiliates	1,304	2,656
Advances to affiliate	470,953	312,165
Trade and other	124,327	125,775
Transportation and exchange gas receivables	4,902	2,876
Inventories	47,469	45,918
Regulatory assets	30,998	36,706
Other	16,215	14,342
Total current assets	696,275	540,623
Investments, at cost plus equity in undistributed earnings	53,666	55,603
Property, Plant and Equipment:
Natural gas transmission plant	8,775,468	8,506,189
Less-Accumulated depreciation and amortization	3,051,284	2,954,276
Total property, plant and equipment, net	5,724,184	5,551,913
Other Assets:
Regulatory assets	275,581	214,912
Other	51,684	47,764
Total other assets	327,265	262,676
Total assets	6,801,390	6,410,815
Payables:
Affiliates	27,417	32,006
Trade and other	123,931	119,307
Transportation and exchange gas payables	1,646	3,513
Reserve for rate refunds	68,407	0
Accrued liabilities	152,865	139,333
Total current liabilities	374,266	294,159
Long-Term Debt	1,428,422	1,428,323
Other Long-Term Liabilities:
Asset retirement obligations	237,373	253,398
Regulatory liabilities	256,458	232,888
Other	19,616	5,339
Total other long-term liabilities	513,447	491,625
Contingent Liabilities and Commitments (Note 2)
Owner's Equity:
Member's capital	2,196,213	1,993,412
Retained earnings	2,289,360	2,204,018
Accumulated other comprehensive loss	(318)	(722)
Total owner's equity	4,485,255	4,196,708
Total liabilities and owner's equity	$ 6,801,390	$ 6,410,815