10.

Additional Balance Sheet Detail

The following table summarizes components of selected balance sheet accounts as of the dates presented:

	As of December 31,
	2011		2010
Other current assets:
Tubular inventory and well materials	$	14,251	$	3,600
Prepaid expenses		699		633
	$	14,950	$	4,233
Other assets:
Debt issuance costs	$	16,993	$	14,300
Long-term investments - Rabbi Trust ¹		3,088		6,440
Other		51		47
	$	20,132	$	20,787
Accounts payable and accrued liabilities:
Trade accounts payable	$	30,186	$	33,831
Drilling costs		30,948		31,770
Royalties		15,235		9,308
Production and franchise taxes		3,495		6,012
Compensation ^{2, 3}		5,186		9,631
Interest		5,964		2,977
Other		3,490		6,132
	$	94,504	$	99,661
Other liabilities:
Asset retirement obligations	$	6,283	$	7,364
Defined benefit pension obligations ²		1,763		1,766
Postretirement health care benefit obligations ²		3,022		2,976
Deferred compensation ¹		3,172		6,952
Other		1,647		900
	$	15,887	$	19,958

¹ Represents the assets and liabilities of the Company's nonqualified supplemental employee retirement savings plan. Assets of the plan are held in a Rabbi Trust. Shares of the Company's common stock held by the Rabbi Trust are presented as Treasury stock carried at cost.

² Includes the combined unfunded benefit obligations under the Company's defined benefit pension and postretirement health care plans of $5.4 million as of December 31, 2011 and 2010. The expense recognized with respect to these plans was $0.4 million, $0.6 million and $0.6 million, for the years ended December 31, 2011, 2010 and 2009, respectively.

³ Includes employer matching obligations under the Company's defined contribution retirement plan of $0.3 million as of December 31, 2011 and 2010. The expense recognized with respect to this plan was $1.2 million, $1.7 million and $2.3 million for the years ended December 31, 2011, 2010 and 2009, respectively.