Supplemental Cash Flow Information - Summary of Supplemental Cash Flow Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Supplemental Cash Flow Elements [Abstract]
Cash paid for interest, net of amounts capitalized	$ 86	$ 73	$ 40
Cash paid for income taxes, net of income tax refunds	2	2	1
Property, plant and equipment acquired with accounts payable	12	43	27
Other non-cash additions of property, plant and equipment	(8)	(4)	(1)
Noncash or Part Noncash Acquisition, Fixed Assets Acquired	0	65	0
Non-cash excess purchase price in March 2014 Transactions and March 2013 Eagle Ford system transaction	$ 0	$ 160	$ 125
Noncash Investing and Financing Activities Related Text	0	0	1