Summarized Financial Information for Reportable Segments (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Segment Reporting Information [Line Items]
Capital expenditures	$ 251,539		$ 274,640		$ 521,170		$ 545,594
Marcellus
Segment Reporting Information [Line Items]
Capital expenditures	9,347	[1]	5	[2]	15,802	[3]	189	[4]
Marcellus | Investments In Unconsolidated Affiliates
Segment Reporting Information [Line Items]
Capital expenditures	37,700		75,900		70,900		169,100
Niobrara
Segment Reporting Information [Line Items]
Capital expenditures	57,860	[5]	11,671	[6]	88,518	[7]	23,197	[8]
Niobrara | Attributable to Noncontrolling Interest Owners
Segment Reporting Information [Line Items]
Capital expenditures	28,900		5,800		44,900		11,600
Utica
Segment Reporting Information [Line Items]
Capital expenditures	85,541	[9]	94,023	[10]	181,179	[11]	159,779	[12]
Utica | Investments In Unconsolidated Affiliates
Segment Reporting Information [Line Items]
Capital expenditures	75,700		112,000		151,900		184,000
Utica | Attributable to Noncontrolling Interest Owners
Segment Reporting Information [Line Items]
Capital expenditures	28,400		33,800		59,300		55,800
Mid-Continent
Segment Reporting Information [Line Items]
Capital expenditures	22,434		29,134	[13]	39,456		68,130	[14]
Mid-Continent | Investments In Unconsolidated Affiliates
Segment Reporting Information [Line Items]
Capital expenditures			$ 2,300				$ 2,600

[1] Amount excludes $37.7 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates.

[2] Amount excludes $75.9 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates.

[3] Amount excludes $70.9 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates.

[4] Amount excludes $169.1 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates.

[5] Amount includes $28.9 million of capital expenditures attributable to noncontrolling interest owners.

[6] Amount includes $5.8 million of capital expenditures attributable to noncontrolling interest owners.

[7] Amount includes $44.9 million of capital expenditures attributable to noncontrolling interest owners.

[8] Amount includes $11.6 million of capital expenditures attributable to noncontrolling interest owners.

[9] Amount excludes $75.7 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates and includes $28.4 million of capital expenditures attributable to noncontrolling interest owners.

[10] Amount excludes $112.0 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates and includes $33.8 million of capital expenditures attributable to noncontrolling interest owners.

[11] Amount excludes $151.9 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates and includes $59.3 million of capital expenditures attributable to noncontrolling interest owners.

[12] Amount excludes $184.0 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates and includes $55.8 million of capital expenditures attributable to noncontrolling interest owners.

[13] Amount excludes $2.3 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates.

[14] Amount excludes $2.6 million for the Partnership’s share of capital expenditures included in investments in unconsolidated affiliates.