Other Commitments and Contingencies - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2013
Other Contingencies And Commitments [Line Items]
Total liabilities to tangible net worth minimum times	3.75
Fixed charge coverage ratio minimum times	1.5
Time to cure ratio	30 days
Funds from operations interest coverage ratio minimum times	2
Total debt to capital maximum	65
Maximum authorized liability under such guarantees and letters of credit	$ 45,000,000
Aggregate guaranteed amount	30,700,000
Amount of letter of credit to our current primary insurance company	304,000
Guarantees expiring date	June 1, 2013
Texas Eastern Transmission, LP [Member]
Other Contingencies And Commitments [Line Items]
Amount of letter of credit to our current primary insurance company	2,300,000
Letter of credit one [Member]
Other Contingencies And Commitments [Line Items]
Amount of letter of credit to our current primary insurance company	1,000,000
Letter of credit two [Member]
Other Contingencies And Commitments [Line Items]
Amount of letter of credit to our current primary insurance company	$ 400,000
Issued letter of credit expiry date	Dec. 02, 2013