Summary of Signigicant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2013

Accounting Policies [Abstract]

Property and Equipment

(in thousands)	September 30, 2013			December 31, 2012
Property and Equipment
Proved oil and gas properties	$	5,474,748		$	5,058,524
Unproved oil and gas properties	90,359			92,579
Furniture, fixtures, and other equipment	41,993			41,690
Less – Accumulated depreciation, depletion, and amortization	(3,034,614		)	(2,847,773		)
Property and Equipment, Net	$	2,572,486		$	2,345,020

Accounts Payable and Accrued Liabilities

	September 30, 2013		December 31, 2012
Trade accounts payable (1)	$	34,497	$	31,128
Accrued operating expenses	13,173		14,647
Accrued payroll costs	10,782		12,297
Asset retirement obligation – current portion	8,119		7,134
Accrued taxes	12,292		5,373
Other payables	2,745		4,799
Total accounts payable and accrued liabilities	$	81,608	$	75,378

(1) Included in “trade accounts payable” are liabilities of approximately $11.4 million and $13.3 million at September 30, 2013 and December 31, 2012, respectively, for outstanding checks.

Roll-forward of our asset retirement obligations

	2013
Asset Retirement Obligation recorded as of January 1	$	86,777
Accretion expense	4,732
Liabilities incurred for new wells and facilities construction	1,550
Reductions due to sold and abandoned wells and facilities	(14,010		)
Revisions in estimates	(2,302		)
Asset Retirement Obligation as of September 30,	$	76,747