CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) (USD $) In Millions, except Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Operating Revenues:
Gas transportation	$ 244.3	$ 227.9	$ 534.8	$ 499.8
Parking and lending	3.1	8.9	6.3	18.3
Gas storage	11.7	13.3	25.5	28.4
Other	2.9	6.6	6.4	10.7
Total operating revenues	262.0	256.7	573.0	557.2
Operating Costs and Expenses:
Fuel and gas transportation	28.2	24.2	52.0	54.1
Operation and maintenance	42.1	34.0	77.2	63.4
Administrative and general	33.7	29.9	70.8	65.6
Depreciation and amortization	56.7	53.7	113.1	107.1
Asset impairment	28.5	2.2	28.5	2.5
Net loss on disposal of operating assets	(3.0)	0	1.4	1.1
Taxes other than income taxes	21.2	20.7	44.9	44.0
Total operating costs and expenses	207.4	164.7	387.9	337.8
Operating income	54.6	92.0	185.1	219.4
Other Deductions (Income):
Interest expense	37.6	35.7	75.9	70.9
Interest expense - affiliates	2.0	2.0	4.0	4.0
Loss on debt extinguishment	0	0	7.4	0
Interest income	(0.1)	(0.2)	(0.2)	(0.3)
Miscellaneous other income, net	(0.1)	0	(0.4)	(0.1)
Total other deductions	39.4	37.5	86.7	74.5
Income before income taxes	15.2	54.5	98.4	144.9
Income taxes	0	0.1	0.2	0.2
Net Income	$ 15.2	$ 54.4	$ 98.2	$ 144.7
Basic and diluted net income per unit:
Common units	$ 0.07	$ 0.28	$ 0.49	$ 0.74
Class B units	$ (0.16)	$ 0.07	$ 0.04	$ 0.32
Cash distribution declared and paid to common units	$ 0.5225	$ 0.505	$ 1.0425	$ 1.005
Cash distribution declared and paid to class B units	$ 0.30	$ 0.30	$ 0.60	$ 0.60
Weighted-average number of units outstanding:
Common units	172.0	169.7	170.9	169.7
Class B units	22.9	22.9	22.9	22.9