Business Segments - Segment Information (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014		Dec. 31, 2013
Segment Reporting Information [Line Items]
Total operating revenues	$ 435	$ 465	$ 430	$ 568	$ 881	$ 868	$ 812	$ 1,081	$ 1,898	$ 3,642		$ 3,051
Gross margin									652	847	[1]	625
Operating and maintenance expense									(214)	(216)		(215)
Depreciation and amortization expense									(120)	(110)		(95)
General and administrative expense									(85)	(64)		(63)
Goodwill, Impairment Loss									(82)	0		0
Earnings from unconsolidated affiliates									173	75		33
Other Operating Income (Expense), Net									(4)	(3)		(8)
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 attributable to partners	90	71	(2)	$ 69	199	$ 116	$ 29	$ 79	228	423		200
Unrealized Gain (Loss) on Derivatives and Commodity Contracts									(131)	86		(36)
Non-cash lower of cost or market adjustments									8	24		4
Capital expenditures									281	338		363
Acquisition expenditures										775		782
Investments in unconsolidated affiliates, net									62	151		242
Total long-term assets	5,171				5,132				5,171	5,132
Current assets	306				590				306	590
Total assets	5,477				5,722				5,477	5,722
Natural Gas Services [Member]
Segment Reporting Information [Line Items]
Total operating revenues									1,618	3,163		2,598
Gross margin									515	756		501
Operating and maintenance expense									(184)	(189)		(184)
Depreciation and amortization expense									(109)	(101)		(87)
General and administrative expense									0	0		0
Goodwill, Impairment Loss		$ (33)	$ (49)						(82)	0
Earnings from unconsolidated affiliates									55	5		1
Other Operating Income (Expense), Net									(8)	(2)		(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 attributable to partners									182	455		213
Unrealized Gain (Loss) on Derivatives and Commodity Contracts									(133)	89		(36)
Non-cash lower of cost or market adjustments									6	11		2
Capital expenditures									240	297		334
Acquisition expenditures										102		696
Investments in unconsolidated affiliates, net									15	75		133
Total long-term assets	4,362				3,609				4,362	3,609
NGL Logistics [Member]
Segment Reporting Information [Line Items]
Total operating revenues									80	73		73
Gross margin									80	73		72
Operating and maintenance expense									(20)	(16)		(16)
Depreciation and amortization expense									(8)	(7)		(6)
General and administrative expense									0	0		0
Goodwill, Impairment Loss									0	0
Earnings from unconsolidated affiliates									118	70		32
Other Operating Income (Expense), Net									4	(1)		(3)
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 attributable to partners									174	119		79
Unrealized Gain (Loss) on Derivatives and Commodity Contracts									0	0		0
Non-cash lower of cost or market adjustments									0	0		0
Capital expenditures									37	25		24
Acquisition expenditures										673		86
Investments in unconsolidated affiliates, net									47	76		109
Total long-term assets	679				1,364				679	1,364
Wholesale Propane Logistics [Member]
Segment Reporting Information [Line Items]
Total operating revenues									200	406		380
Gross margin									57	18		52
Operating and maintenance expense									(10)	(11)		(15)
Depreciation and amortization expense									(3)	(2)		(2)
General and administrative expense									0	0		0
Goodwill, Impairment Loss									0	0
Earnings from unconsolidated affiliates									0	0		0
Other Operating Income (Expense), Net									0	0		(4)
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 attributable to partners									44	5		31
Unrealized Gain (Loss) on Derivatives and Commodity Contracts									3	(3)		(1)
Non-cash lower of cost or market adjustments									2	13		2
Capital expenditures									4	16		5
Acquisition expenditures										0		0
Investments in unconsolidated affiliates, net									0	0		0
Total long-term assets	120				118				120	118
Other [Member]
Segment Reporting Information [Line Items]
Total operating revenues									0	0		0
Gross margin									0	0	[1]	0
Operating and maintenance expense									0	0		0
Depreciation and amortization expense									0	0		0
General and administrative expense									(85)	(64)		(63)
Goodwill, Impairment Loss									0
Earnings from unconsolidated affiliates									0	0		0
Other Operating Income (Expense), Net									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 attributable to partners									(172)	(156)		(123)
Unrealized Gain (Loss) on Derivatives and Commodity Contracts									(1)	0		1
Non-cash lower of cost or market adjustments									0	0		0
Capital expenditures									0	0		0
Acquisition expenditures										0		0
Investments in unconsolidated affiliates, net									0	0		$ 0
Total long-term assets	$ 10				$ 41				$ 10	$ 41

[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.