Summary of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2011

Summary of Significant Accounting Policies [Abstract]

Property and Equipment

(in thousands)	June 30, 2011			December 31, 2010
Property and Equipment
Proved oil and gas properties	$	4,080,741		$	3,835,173
Unproved oil and gas properties		81,303			78,429
Furniture, fixtures, and other equipment		38,959			37,505
Less — Accumulated depreciation, depletion, and amortization		(2,487,813	)		(2,378,262	)
Property and Equipment, Net	$	1,713,190		$	1,572,845

Accounts Payable and Accrued Liabilities

(in thousands)	June 30, 2011		December 31, 2010
Trade accounts payable (1)	$	16,038	$	22,459
New Zealand deferred revenue		—		10,000
Accrued expenses		16,581		19,284
Asset retirement obligation — current portion		7,986		8,708
Accrued severance taxes		4,130		10,253
Other accrued liabilities		7,477		4,890
Total accounts payable and accrued liabilities	$	52,212	$	75,594

(1) Included in “trade accounts payable” are liabilities of approximately $11.1 million and $8.1 million at June 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			($137	)
Change in fair value of cash flow hedges		(333	)		121			(212	)
Effect of cash flow hedges settled during the period		883			(324	)		559
Other comprehensive income at June 30, 2011	$	332		$	(122	)	$	210

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		2,299			1,929
Liabilities incurred for new wells and facilities construction		213			524
Reductions due to sold and abandoned wells		(258	)		(75	)
Revisions in estimated cash flows		(1,573	)		—
Asset Retirement Obligation as of June 30	$	79,560		$	66,614