Summarized Financial Information for Reportable Segments (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Segment Reporting Information [Line Items]
Capital expenditures	$ 265,517		$ 90,711		$ 811,111		$ 231,632
Marcellus
Segment Reporting Information [Line Items]
Capital expenditures	10	[1]		[2]	199	[3]		[4]
Marcellus | Investments in Unconsolidated Affiliates
Segment Reporting Information [Line Items]
Capital expenditures	75,400		115,500		244,500		290,700
Niobrara
Segment Reporting Information [Line Items]
Capital expenditures	20,839	[5]			44,036	[6]
Niobrara | Attributable To Noncontrolling Interest Owners
Segment Reporting Information [Line Items]
Capital expenditures	10,400				22,000
Utica
Segment Reporting Information [Line Items]
Capital expenditures	102,161	[7]			261,940	[8]
Utica | Investments in Unconsolidated Affiliates
Segment Reporting Information [Line Items]
Capital expenditures	103,500				287,500
Utica | Attributable To Noncontrolling Interest Owners
Segment Reporting Information [Line Items]
Capital expenditures	36,400				92,200
Mid-Continent
Segment Reporting Information [Line Items]
Capital expenditures	20,450	[9]	58,352		88,580	[10]	113,048
Mid-Continent | Investments in Unconsolidated Affiliates
Segment Reporting Information [Line Items]
Capital expenditures	$ 1,300				$ 3,900

[1] Amount excludes $75.4 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates.

[2] Amount excludes $115.5 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates.

[3] Amount excludes $244.5 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates.

[4] Amount excludes $290.7 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates

[5] Amount includes $10.4 million of capital expenditures attributable to noncontrolling interest owners.

[6] Amount includes $22.0 million of capital expenditures attributable to noncontrolling interest owners.

[7] Amount excludes $103.5 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates and includes $36.4 million of capital expenditures attributable to noncontrolling interest owners.

[8] Amount excludes $287.5 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates and includes $92.2 million of capital expenditures attributable to noncontrolling interest owners.

[9] Amount excludes $1.3 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates.

[10] Amount excludes $3.9 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates.