Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2011

Summary of Significant Accounting Policies [Abstract]

Property and Equipment

(in thousands)	September 30, 2011			December 31, 2010
Property and Equipment
Proved oil and gas properties	$	4,259,439		$	3,835,173
Unproved oil and gas properties		79,439			78,429
Furniture, fixtures, and other equipment		37,344			37,505
Less — Accumulated depreciation, depletion, and amortization		(2,540,613	)		(2,378,262	)
Property and Equipment, Net	$	1,835,609		$	1,572,845

Accounts Payable and Accrued Liabilities

(in thousands)	September 30, 2011		December 31, 2010
Trade accounts payable (1)	$	39,923	$	22,459
New Zealand deferred revenue		—		10,000
Accrued expenses		24,559		21,801
Asset retirement obligation — current portion		12,274		8,708
Accrued taxes		7,173		11,156
Deposit for property disposition		5,350		—
Other payables		1,472		1,470
Total accounts payable and accrued liabilities	$	90,751	$	75,594

(1) Included in “trade accounts payable” are liabilities of approximately $21.0 million and $8.1 million at September 30, 2011 and December 31, 2010, respectively, for outstanding checks. This represents the amounts by which checks were issued, but not presented by vendors to the Company’s banks for collection, exceeded balances in the applicable disbursement bank accounts.

Accumulated other comprehensive income (loss) and related tax effects for 2011 (in thousands)

	Gross Value			Tax Effect			Net of Tax Value
Other comprehensive loss at December 31, 2010	$	(218	)	$	81		$	(138	)
Change in fair value of cash flow hedges		(405	)		148			(257	)
Effect of cash flow hedges settled during the period		623			(229	)		394
Other comprehensive income at September 30, 2011	$	—		$	—		$	—

Roll-forward of our asset retirement obligation

(in thousands)	2011			2010
Asset Retirement Obligation recorded as of January 1	$	78,879		$	64,236
Accretion expense		3,482			2,927
Liabilities incurred for new wells and facilities construction		490			1,018
Reductions due to sold and abandoned wells		(335	)		(463	)
Revisions in estimated cash flows		20,995			—
Asset Retirement Obligation as of September 30	$	103,511		$	67,718