8. Asset Impairment Charges
Asset impairment charges incurred during the year ended December 31, 2019 were primarily the result of impairing the remaining NantHealth acquired customer relationship intangible balance of $8.1 million. We also recognized non-cash impairment charges of $2.7 million on the retirement of certain hosting assets due to data center migrations.
Impairment of long-term investments during the year ended December 31, 2019 consisted of an impairment of $1.7 million associated with one of our long-term equity investments. We also recovered $1.0 million from one of our long-term equity investments investment that we had previously impaired. We also recorded a goodwill impairment charge of $25.7 million related to our HHS reporting unit. Refer to Note 7, “Goodwill and Intangible Assets” for further information regarding this impairment.
We incurred several non-cash asset impairment charges during the year ended December 31, 2018. We recorded non-cash asset impairment charges of $33.2 million related to the write-off of capitalized software as a result of our decision to discontinue several software development projects.
We also recorded $22.9 million of non-cash asset impairment charges related to our acquisition of the patient/provider engagement solutions business from NantHealth in 2017, which included the write-downs of $2.2 million of acquired technology and $20.7 million, representing the unamortized value assigned to the modification of our existing commercial agreement with NantHealth, as we no longer expect to recover the value assigned to these assets.
The remaining $2.1 million of non-cash asset impairment charges recorded during the year ended December 31, 2018 relate to the disposal of fixed assets as a result of relocating and consolidating business functions and locations from recent acquisitions.
We recorded a goodwill impairment charge of $13.5 million related to NantHealth during the year ended December 31, 2018. Refer to Note 7, “Goodwill and Intangible Assets” for further information regarding this impairment. We recognized non-cash impairment charges of $15.5 million in 2018 related to two of our cost-method equity investments and a related note receivable. These charges equaled the cost bases of the investments and the related note receivable prior to the impairment.
We recorded non-cash charges of $165.3 million during the year ended December 31, 2017, including impairment charges of $144.6 million associated with two of the Company’s long-term investments based on management’s assessment of the likelihood of near-term recovery of the investments’ value.
The majority of the impairment charges related to our investment in NantHealth common stock. We realized an additional $20.7 million loss upon the final disposition of the NantHealth common stock in connection with our acquisition of certain assets related to NantHealth’s provider/patient engagement solutions business. Refer to Note 4, “Business Combinations and Other Investments” and Note 14, “Accumulated Other Comprehensive Loss,” for further information regarding these impairments.
The following table summarizes the non-cash asset impairment charges recorded during the periods indicated and where they appear in the corresponding consolidated statements of operations:
Table:
 |  | Year Ended December 31, | 
(In thousands) | 2019 | 2018 | 2017
Asset impairment charges | $ 10,837 | $ 58,166 | $ 0
Goodwill impairment charge | $ 25,700 | $ 13,466 | $ 0
Impairment of long-term investments | $ 651 | $ 15,487 | $ 165,290


Question: What caused the asset impairment charges in 2019?
Answer: primarily the result of impairing the remaining NantHealth acquired customer relationship intangible balance of $8.1 million.