Commitments and Contingencies - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) MMcf / d MBbls / d	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Commitments And Contingencies Disclosure [Line Items]
Rent expense under operating leases | $	$ 15.9	$ 13.3	$ 13.1
Minimum remaining terms of leases on undeveloped acreage, in years	3 years
Maximum remaining terms of leases on undeveloped acreage, in years	5 years
2016
Commitments And Contingencies Disclosure [Line Items]
Delivery commitments contingent upon pipeline construction or modification per day | MBbls / d	20
Minimum
Commitments And Contingencies Disclosure [Line Items]
Transportation and gathering commitments contingent upon pipeline construction or modification, term of contract	6 years
Maximum
Commitments And Contingencies Disclosure [Line Items]
Transportation and gathering commitments contingent upon pipeline construction or modification, term of contract	20 years
Maximum | 2018
Commitments And Contingencies Disclosure [Line Items]
Delivery commitments contingent upon pipeline construction or modification per day | MBbls / d	30
Maximum | 2020
Commitments And Contingencies Disclosure [Line Items]
Delivery commitments contingent upon pipeline construction or modification per day | MBbls / d	45
Natural Gas | 2026
Commitments And Contingencies Disclosure [Line Items]
Transportation commitments contingent upon pipeline construction or modification	2,000
Natural Gas | 2032
Commitments And Contingencies Disclosure [Line Items]
Transportation commitments contingent upon pipeline construction or modification	1,300
Natural Gas | 2037
Commitments And Contingencies Disclosure [Line Items]
Transportation commitments contingent upon pipeline construction or modification	400
Natural Gas | 2017 through 2032
Commitments And Contingencies Disclosure [Line Items]
Gathering commitments contingent upon pipeline construction or modification	400
Natural Gas | 2017
Commitments And Contingencies Disclosure [Line Items]
Delivery commitments contingent upon pipeline construction or modification per day	50
Natural Gas | Minimum | 2019
Commitments And Contingencies Disclosure [Line Items]
Delivery commitments contingent upon pipeline construction or modification per day	200
Natural Gas | Maximum | 2019
Commitments And Contingencies Disclosure [Line Items]
Delivery commitments contingent upon pipeline construction or modification per day	300
Ethane | 2031
Commitments And Contingencies Disclosure [Line Items]
Transportation commitments contingent upon pipeline construction or modification | MBbls / d	20
Propane | 2031
Commitments And Contingencies Disclosure [Line Items]
Transportation commitments contingent upon pipeline construction or modification | MBbls / d	20