10. Long-Lived Asset Impairment

We review long-lived assets, including property, plant and equipment and identifiable intangibles that are being amortized, for impairment whenever events or changes in circumstances, including the removal of compressor units from our active fleet, indicate that the carrying amount of an asset may not be recoverable.

During the three and nine months ended September 30, 2017 and 2016 we reviewed the future deployment of our idle compression assets for units that were not of the type, configuration, condition, make or model that are cost efficient to maintain and operate. Based on these reviews, we determined that certain idle compressor units would be retired from the active fleet. The retirement of these units from the active fleet triggered a review of these assets for impairment, and as a result of our review, we recorded an asset impairment to reduce the book value of each unit to its estimated fair value. The fair value of each unit was estimated based on either the expected net sale proceeds compared to other fleet units we recently sold and/or a review of other units recently offered for sale by third parties, or the estimated component value of the equipment we plan to use.

In connection with our review of our idle compression assets during the three and nine months ended September 30, 2017 and 2016, we evaluated for impairment idle units that had been culled from our fleet in prior years and were available for sale. Based upon that review, we reduced the expected proceeds from disposition for certain of the remaining units and recorded additional impairment to reduce the book value of each unit to its estimated fair value.

The following table presents the results of our impairment review of compressor units for the three and nine months ended September 30, 2017 and 2016 (dollars in thousands):



	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
Idle compressor units retired from the active fleet	50		60		190		270
Horsepower of idle compressor units retired from the active fleet	20,000		25,000		71,000		97,000
Impairment recorded on idle compressor units retired from the active fleet	$	5,934	$	9,081	$	19,686	$	29,674
Additional impairment recorded on available-for-sale compressor units previously culled	$	—	$	7,632	$	—	$	10,707

In addition to the impairment discussed above, during the three and nine months ended September 30, 2017, $0.8 million of leasehold improvements and furniture and fixtures were impaired in conjunction with the relocation of our corporate office during the third quarter. See Note 12 (“Corporate Office Relocation”) for further details.