Commitments and Contingencies 2 Narrative (Details) (USD $)	0 Months Ended	1 Months Ended	12 Months Ended			3 Months Ended		12 Months Ended	3 Months Ended		12 Months Ended
	Jul. 07, 2011	Jan. 27, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Jun. 30, 2011 East End Project [Member]	Jun. 30, 2008 East End Project [Member] miles	Dec. 31, 2011 Southern Union Gas Services [Member]	Mar. 31, 2010 Jal 3 Facility [Member]	Mar. 31, 2010 Jal 4 Facility [Member]	Dec. 31, 2011 North Attleboro Site [Member]	Dec. 31, 2011 Missouri Safety Program [Member]	Dec. 31, 2010 Missouri Safety Program [Member]	Dec. 31, 2009 Missouri Safety Program [Member]	Dec. 31, 2011 Attorney General of Commonwealth [Member]
Commitments And Contingencies [Line Items]
Site Contingency Loss Exposure Not Accrued Best Estimate											$ 10,900,000
Pipelines Installed							31
Cost Overruns Recovery							50,000,000
Alleged Underpayments							18,000,000
Proceeds From Legal Settlements		82,700,000			1,900,000	16,000,000
Reimbursement Cost Overruns						9,000,000
Legal Fees	18,500,000
Percentage Of Recovery	50
Reimbursement Costs															150,000
Estimated Litigation Liability			28,300,000	26,900,000
Recovery Units						three
Alleged Violations									5,507,583	518,720,000
Emission Control Equipment								50,000,000
Emission Control Equipment Years								nine
Environmental Remediation Expense			3,200,000	4,500,000	12,000,000
Hurricane Related Expenses			141,000,000
Insurance Recoveries			64,700,000
Capital Replacement And Retirement Expenditure Incurred			141,000,000	134,000,000	110,000,000
Property Insurance Deductible			10,000,000
Insurance Aggregate Exposure Limit			750,000,000
Estimated Payout Percentage			70.00%
Interim Payout Rate			50.00%
Recorded Unconditional Purchase Obligation			608,600,000
Capital Expenditures												13,800,000	13,600,000	14,400,000
Estimated Future Capital Expenditures												$ 94,800,000
Capital Expenditures Years												10
Percentage Service Lines												33.00%