Consolidated Statement of Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Operating Revenues:
Natural gas sales	$ 108,359	$ 99,346	$ 96,713
Natural gas transportation	983,554	930,704	891,841
Natural gas storage	142,556	146,820	144,978
Other	8,045	5,125	25,741
Total operating revenues	1,242,514	1,181,995	1,159,273
Operating Costs and Expenses:
Cost of natural gas sales	108,359	99,346	96,682
Cost of natural gas transportation	35,674	32,231	16,959
Operation and maintenance	264,324	239,643	249,625
Administrative and general	158,524	158,006	164,831
Depreciation and amortization	259,660	252,049	246,247
Taxes - other than income taxes	48,434	46,064	35,809
Other expense, net	12,988	15,189	13,816
Total operating costs and expenses	887,963	842,528	823,969
Operating Income	354,551	339,467	335,304
Other (Income) and Other Deductions:
Interest expense - affiliate	262	353	387
Interest expense - other	94,920	94,620	93,993
Interest income - affiliate	(29)	(2,231)	(19,090)
Interest income - other	(2,119)	(882)	(1,185)
Allowance for equity and borrowed funds used during construction (AFUDC)	(15,339)	(12,349)	(11,982)
Equity in earnings of unconsolidated affiliates	(5,164)	(5,805)	(5,757)
Miscellaneous other (income) deductions, net	2,362	(5,015)	(1,419)
Total other (income) and other deductions	74,893	68,691	54,947
Net Income	$ 279,658	$ 270,776	$ 280,357