Related Party Transactions - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014 Centennial	Sep. 30, 2013 Centennial	Sep. 30, 2014 Centennial	Sep. 30, 2013 Centennial	Dec. 31, 2013 Centennial	Sep. 30, 2014 Explorer	Sep. 30, 2014 LOCAP	Sep. 30, 2014 LOOP	Sep. 30, 2014 TAAE	Oct. 01, 2013 TAAE	Sep. 30, 2014 TACE	Sep. 30, 2014 TAME
Related Party Transaction [Line Items]
Equity method investments, ownership percentage	50.00%		50.00%			25.00%	59.00%	51.00%	43.00%	43.00%	60.00%	67.00%
Operating pipeline revenue from related parties included in other income, Centennial	$ 0	$ 0	$ 1	$ 1
Long-term receivable from related party	$ 1		$ 1		$ 2