Document And Entity Information	3 Months Ended
	Mar. 31, 2013
Document Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Entity Registrant Name	Southern Union Co
Entity Central Index Key	0000203248
Document Period End Date	Mar. 31, 2013
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q1
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding	0