Debt Obligations (Southern Union Credit Facility) (Narrative) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013
Southern Union Credit Facility [Member]
Line of Credit Facility [Line Items]
Amount Outstanding	$ 240
Weighted average interest rate on amount outstanding	1.83%
Southern Union [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 700