Acquisitions and Divestitures (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended					1 Months Ended	12 Months Ended		1 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Creek, Love, and Carter Counties, Oklahoma	Dec. 31, 2013 Texas County, Oklahoma	May 30, 2012 Southern Oklahoma	Dec. 31, 2013 Cabot Oil & Gas Corporation Panhandle Marmaton Play acre	Dec. 31, 2012 Cabot Oil & Gas Corporation Panhandle Marmaton Play	Nov. 30, 2011 Charger Resources, LLC Rocky Mountains	Nov. 30, 2011 Green Country Supply, Inc.
Cabot Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired	$ 153,858	$ 0	$ 0				$ 153,858
Oil and natural gas acres, gross							131,000
Oil and natural gas acres, net							66,000
Acquisition related costs							951
Purchase Price Allocation
Proved oil and natural gas properties							67,275
Unevaluated oil and natural gas properties							87,663
Asset retirement obligations							(1,080)
Fair value of net identifiable assets acquired							153,858
Unaudited Pro Forma Information
Revenues							690,564	599,344
Operating Expenses							448,751	402,677
Net income							76,552	78,089
Proceeds from sale of oil and gas properties	109,710			61,440	17,800	37,000			33,100
Proceeds from sale of other assets										4,433
Gain on sale of assets	$ 670	$ 149	$ 1,284							$ 2,630