Summary of Business and Basis of Presentation - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2014 Well Segment
Summary Of Business And Accounting Policies [Line Items]
Number of reporting segments	4
Number of natural gas producing wells and gas gathering assets	160
EWR Subsidiary [Member]
Summary Of Business And Accounting Policies [Line Items]
Gross percentage of working interest	51.00%
Average net revenue interest, percentage	43.00%
Natural Gas Operations [Member]
Summary Of Business And Accounting Policies [Line Items]
Annual distribution of natural gas	36,000,000
Natural gas customers	73,000
Marketing & Production Operations [Member]
Summary Of Business And Accounting Policies [Line Items]
Annually market of natural gas	1,500,000