Business Segments - Additional Information (Detail) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) Segment Project	Dec. 31, 2014 USD ($) Project		Dec. 31, 2013 USD ($)
Segment Reporting Information [Line Items]
Total operating revenues	$ 435	$ 465	$ 430	$ 568	$ 881	$ 868	$ 812	$ 1,081	$ 1,898	$ 3,642		$ 3,051
Number of reporting segments | Segment									3
Ownership interest percentage					100.00%					100.00%
Number of owned and operated rail terminals | Project									6
Number of owned marine import terminals | Project									1
Number of leased marine terminals | Project									1
Pipeline Terminals | Project										1
Gross margin									$ 652	$ 847	[1]	625
Other Cost and Expense, Operating									(214)	(216)		(215)
Depreciation, Depletion and Amortization, Nonproduction									(120)	(110)		(95)
General and Administrative Expense									(85)	(64)		(63)
Earnings from unconsolidated affiliates									173	75		33
Interest expense									(92)	(86)		(52)
Income tax expense									5	(6)		(8)
Net income	94	72	(2)	69	$ 203	116	29	89	233	437		217
Net income attributable to noncontrolling interests	(4)	(1)	0	0	(4)	0	0	(10)	(5)	(14)		(17)
Net Income (Loss) Attributable to Parent	$ 90	$ 71	$ (2)	$ 69	$ 199	$ 116	$ 29	$ 79	228	423		200
Unrealized Gain (Loss) on Derivatives and Commodity Contracts									(131)	86		(36)
Capital expenditures									281	338		363
Acquisition expenditures										775		782
Investments in unconsolidated affiliates, net									$ 62	151		242
Sand Hills Pipeline [Member]
Segment Reporting Information [Line Items]
Equity Method Investment, Ownership Percentage	33.33%								33.33%
Natural Gas Services [Member]
Segment Reporting Information [Line Items]
Total operating revenues									$ 1,618	3,163		2,598
Gross margin									515	756		501
Other Cost and Expense, Operating									(184)	(189)		(184)
Depreciation, Depletion and Amortization, Nonproduction									(109)	(101)		(87)
General and Administrative Expense									0	0		0
Earnings from unconsolidated affiliates									55	5		1
Interest expense									0	0		0
Income tax expense									0	0		0
Net income									187	469		230
Net income attributable to noncontrolling interests									(5)	(14)		(17)
Net Income (Loss) Attributable to Parent									182	455		213
Unrealized Gain (Loss) on Derivatives and Commodity Contracts									(133)	89		(36)
Capital expenditures									240	297		334
Acquisition expenditures										102		696
Investments in unconsolidated affiliates, net									$ 15	$ 75		$ 133
Colorado [Member]
Segment Reporting Information [Line Items]
Ownership interest percentage					75.00%					75.00%
Discovery Producer Services LLC [Member]
Segment Reporting Information [Line Items]
Equity Method Investment, Ownership Percentage					40.00%					40.00%
Mont Belvieu 1 Fractionator [Member]
Segment Reporting Information [Line Items]
Equity Method Investment, Ownership Percentage					20.00%					20.00%
Mont Belvieu Enterprise Fractionator [Member]
Segment Reporting Information [Line Items]
Equity Method Investment, Ownership Percentage					12.50%					12.50%
Southern Hills Pipeline [Member]
Segment Reporting Information [Line Items]
Equity Method Investment, Ownership Percentage	33.33%								33.33%
Texas Express [Member]
Segment Reporting Information [Line Items]
Ownership interest percentage in subsidiary										10.00%
Panola [Member]
Segment Reporting Information [Line Items]
Equity Method Investment, Ownership Percentage												15.00%
NGL Logistics [Member]
Segment Reporting Information [Line Items]
Total operating revenues									$ 80	$ 73		$ 73
Gross margin									80	73		72
Other Cost and Expense, Operating									(20)	(16)		(16)
Depreciation, Depletion and Amortization, Nonproduction									(8)	(7)		(6)
General and Administrative Expense									0	0		0
Earnings from unconsolidated affiliates									118	70		32
Interest expense									0	0		0
Income tax expense									0	0		0
Net income									174	119		79
Net income attributable to noncontrolling interests									0	0		0
Net Income (Loss) Attributable to Parent									174	119		79
Unrealized Gain (Loss) on Derivatives and Commodity Contracts									0	0		0
Capital expenditures									37	25		24
Acquisition expenditures										673		86
Investments in unconsolidated affiliates, net									47	76		109
Wholesale Propane Logistics [Member]
Segment Reporting Information [Line Items]
Total operating revenues									200	406		380
Gross margin									57	18		52
Other Cost and Expense, Operating									(10)	(11)		(15)
Depreciation, Depletion and Amortization, Nonproduction									(3)	(2)		(2)
General and Administrative Expense									0	0		0
Earnings from unconsolidated affiliates									0	0		0
Interest expense									0	0		0
Income tax expense									0	0		0
Net income									44	5		31
Net income attributable to noncontrolling interests									0	0		0
Net Income (Loss) Attributable to Parent									44	5		31
Unrealized Gain (Loss) on Derivatives and Commodity Contracts									3	(3)		(1)
Capital expenditures									4	16		5
Acquisition expenditures										0		0
Investments in unconsolidated affiliates, net									0	0		0
Other [Member]
Segment Reporting Information [Line Items]
Total operating revenues									0	0		0
Gross margin									0	0	[1]	0
Other Cost and Expense, Operating									0	0		0
Depreciation, Depletion and Amortization, Nonproduction									0	0		0
General and Administrative Expense									(85)	(64)		(63)
Earnings from unconsolidated affiliates									0	0		0
Interest expense									(92)	(86)		(52)
Income tax expense									5	(6)		(8)
Net income									(172)	(156)		(123)
Net income attributable to noncontrolling interests									0	0		0
Net Income (Loss) Attributable to Parent									(172)	(156)		(123)
Unrealized Gain (Loss) on Derivatives and Commodity Contracts									(1)	0		1
Capital expenditures									0	0		0
Acquisition expenditures										0		0
Investments in unconsolidated affiliates, net									$ 0	$ 0		$ 0
Front Range Pipeline [Member]
Segment Reporting Information [Line Items]
Equity Method Investment, Ownership Percentage												33.33%

[1] Gross margin consists of total operating revenues, including commodity derivative activity, less purchases of natural gas, propane and NGLs. Gross margin is viewed as a non-GAAP measure under the rules of the SEC, but is included as a supplemental disclosure because it is a primary performance measure used by management as it represents the results of product sales versus product purchases. As an indicator of our operating performance, gross margin should not be considered an alternative to, or more meaningful than, net income or cash flow as determined in accordance with GAAP. Our gross margin may not be comparable to a similarly titled measure of another company because other entities may not calculate gross margin in the same manner.