Summarized Financial Information for Reportable Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Segment Reporting Information [Line Items]
Revenues	$ 495,078	$ 313,849	$ 292,934	$ 277,078	$ 328,078	$ 260,943	$ 247,242	$ 236,959	$ 1,378,939		$ 1,073,222		$ 608,447
Operating expenses									427,589		338,716		197,639
Depreciation and amortization expense									314,758		296,179		165,517
General and administrative expense									202,796		104,332		67,579
Other operating expense (income)									24,123		2,092		(766)
Operating income									409,673		331,903		178,478
Income (loss) from unconsolidated affiliates									205,082		130,420		67,542
Capital expenditures									999,211		1,058,599		350,500
Total assets	9,143,577				7,917,446				9,143,577		7,917,446		6,561,100
Operating Segments | Barnett
Segment Reporting Information [Line Items]
Revenues									463,645		433,709		395,467
Operating expenses									95,744		96,926		101,703
Depreciation and amortization expense									81,845		97,941		93,343
Operating income									286,056		238,842		200,421
Capital expenditures									13,661		50,627		98,507
Total assets	1,438,080				1,511,405				1,438,080		1,511,405		1,573,789
Operating Segments | Eagle Ford
Segment Reporting Information [Line Items]
Revenues									348,904		278,282		7,232
Operating expenses									74,962		59,059		1,604
Depreciation and amortization expense									56,980		51,433		968
Operating income									216,962		167,790		4,660
Capital expenditures									188,661		316,002		11,796
Total assets	1,277,910				1,172,022				1,277,910		1,172,022		925,694
Operating Segments | Haynesville
Segment Reporting Information [Line Items]
Revenues									160,138		119,209		68,184
Operating expenses									46,171		41,176		15,642
Depreciation and amortization expense									69,488		80,770		33,210
Operating income									44,479		(2,737)		19,332
Capital expenditures									14,459		17,186		23,578
Total assets	1,220,301				1,276,795				1,220,301		1,276,795		1,324,599
Operating Segments | Marcellus Shale
Segment Reporting Information [Line Items]
Revenues									15,136		10,989		783
Operating expenses									12,526		4,834		188
Depreciation and amortization expense									8,182		1,381		6
Operating income									(5,572)		4,774		589
Income (loss) from unconsolidated affiliates									170,236		133,036		67,592
Capital expenditures									42,791	[1]	2,590	[2]
Total assets	1,662,655				1,452,797				1,662,655		1,452,797		1,142,550
Operating Segments | Niobrara
Segment Reporting Information [Line Items]
Revenues									28,329		15,095		116
Operating expenses									14,568		9,090		85
Depreciation and amortization expense									5,418		4,284		79
Operating income									8,343		1,721		(48)
Capital expenditures									213,749	[3]	59,115	[4]	1,967
Total assets	367,132				137,319				367,132		137,319		91,236
Operating Segments | Utica
Segment Reporting Information [Line Items]
Revenues									153,963		44,063		353
Operating expenses									38,348		19,065		159
Depreciation and amortization expense									25,512		9,451		48
Operating income									90,103		15,547		146
Income (loss) from unconsolidated affiliates									24,832		(3,842)		(38)
Capital expenditures									317,638	[5]	342,839	[6]	126
Total assets	1,596,504				1,040,199				1,596,504		1,040,199		356,662
Operating Segments | Mid-Continent
Segment Reporting Information [Line Items]
Revenues									208,819		171,875		136,312
Operating expenses									78,150		70,609		52,979
Depreciation and amortization expense									35,364		36,435		32,042
Operating income									95,305		64,831		51,291
Income (loss) from unconsolidated affiliates									10,014		1,226		(12)
Capital expenditures									100,889	[7]	106,718	[8]	184,285
Total assets	820,576				773,104				820,576		773,104		714,510
Operating Segments | Corporate
Segment Reporting Information [Line Items]
Revenues									5
Operating expenses									67,120		37,957		25,279
Depreciation and amortization expense									31,969		14,484		5,821
General and administrative expense									202,796		104,332		67,579
Other operating expense (income)									24,123		2,092		(766)
Operating income									(326,003)		(158,865)		(97,913)
Capital expenditures									107,363		163,522		30,241
Total assets	$ 760,419				$ 553,805				$ 760,419		$ 553,805		$ 432,060

[1] Amount excludes $147.0 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates.

[2] Amount excludes $289.7 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates

[3] Amount includes $107.6 million of capital expenditures attributable to noncontrolling interest owners.

[4] Amount includes $29.6 million of capital expenditures attributable to noncontrolling interest owners.

[5] Amount excludes $237.2 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates and includes $103.9 million of capital expenditures attributable to noncontrolling interest owners.

[6] Amount excludes $376.8 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates and includes $122.0 million of capital expenditures attributable to noncontrolling interest owners.

[7] Amount excludes $1.0 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates.

[8] Amount excludes $4.9 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates.