Property and equipment

Major classes of property and equipment are shown in the following table. As discussed in “Note 4: Fresh start accounting,” the application of fresh start accounting to our balance sheet on March 21, 2017, resulted in restating our property and equipment to fair value, thus resetting the accumulated depreciation and amortization balance. Property acquired since that date is capitalized and stated at cost. Maintenance and repairs are expensed currently.

Depreciation and amortization are provided in amounts sufficient to relate the cost of depreciable assets to operations over their estimated service lives using the straight-line method. Estimated useful lives of our assets are as follows:



	Useful Life	December 31, 2019		December 31, 2018
Furniture and fixtures	10	$	8	$	520
Automobiles and trucks	5	3,071		3,548
Machinery and equipment	10 — 20 years	3,543		21,482
Office and computer equipment	5 — 10 years	3,363		6,183
Building and improvements	10 — 40 years	693		18,693
		10,678		50,426
Less accumulated depreciation and amortization		3,459		12,449
		7,219		37,977
Land		1,998		5,119
		$	9,217	$	43,096

Impairment of headquarters building and subsequent sales. During the second quarter of 2019, we commenced efforts to locate a buyer for our headquarters building. In conjunction with these efforts, we obtained a third party valuation on the fair value of the property. The valuation appraised the property at an amount lower than its net book value at the time. Based on this market appraisal and our expectations that, more likely than not, the headquarters building would be sold before the end of its useful life, we determined that the net book value of the property would not be recoverable. As a result, we recorded an impairment of $6,407 in June 2019 to write-down the net book value of the property to its fair value based on its market appraisal.

On August 5, 2019, we entered into a real estate purchase and sale agreement for the sale of the building housing our headquarters along with adjacent land, furniture and fixtures. We closed the sale on August 29, 2019, for net proceeds of $11,494 while recognizing an immaterial loss on disposal. The proceeds from the sale were utilized to pay off the outstanding balance of the real estate mortgage note on the property. We incurred a prepayment penalty of $1,624 on the early payoff of the note, which we recorded as a “Loss on extinguishment of debt” on our consolidated statements of operations. Conditioned upon closing of this sale, we entered into a leaseback agreement with the buyer for a portion of the office space, which we discuss in “Note 17: Leases.”

Held for sale. In an effort to further streamline operations, during the fourth quarter of 2019, the Company began transitioning from an internally staffed and resourced oilfield services function to a third party provider solution. As a result, it began to actively market all related company-owned oilfield services machinery and equipment for eventual disposal. Accounting guidance requires us to reflect the disposal group separately on the balance sheet as “Assets held for sale” at carrying value or fair value less cost to sell, whichever is less. The carrying value of assets held for sale is not included in the table above. As a result of determining fair value on the assets held for sale, an impairment loss was recorded for the year ended December 31, 2019 in the amount of $781, which was included in the “Impairment of other assets” in the Statements of Operations. Our held for sale assets as of December 31, 2019 consisted of:



	Carrying value at
	December 31, 2019
Equipment	$	1,572
Vehicles	488
Real estate	800
Total held for sale	$	2,860

Leased compressors. Our property and equipment balance as of December 31, 2018, included CO₂ compressors that were held under finance leases and simultaneously subleased to the buyer of our former EOR oil and natural gas properties. In September 2019, U.S. Bank, the originating lessor, entered into agreements with the Sublessee that resulted in the discharge of all our obligations with respect to these compressor leases and the removal of those assets and elimination of associated debt from our consolidated balance sheet.