6.    Assets Held for Sale, Property and Equipment

As of December 31, 2022, property and equipment are summarized as follows (in thousands):

As of September 30, 2023, assets held for sale are summarized as follows (in thousands):

At the end of the third quarter of 2023, as part of the Company's strategic process for maximizing the value of assets, the Company committed to a plan to prepare and sell all property and equipment held at the Hallbergmoos, Germany location. The Company engaged Stifel to assist with a process to locate a buyer alongside internal efforts to sell the majority of property and equipment held there. The sale of the assets was deemed probable as a result of management's decision, including the estimated timing of sale which was determined to be within a year of the decision. Given the ongoing strategic review, it is unlikely that significant change to the plan will occur. As a result of this decision, the property and equipment met the criteria for held-for-sale accounting as of September 30, 2023. The Company is in the process of obtaining third-party appraisals for the resale value of equipment to be disposed and expects substantially all assets to be disposed by the end of the first quarter of 2024.

The Company recorded impairment charges totaling $14.9 million, of which $1.8 million related to impairment of its right-of-use asset under the Hallbergmoos Lease (see Note 10) with the remaining related to a complete write-off of leasehold improvements and a partial impairment of the Company's other long-lived assets.. The remaining $2.1 million in net book value of its long-lived assets represents the Company's best estimate of the fair value less costs to sell that could be recovered related to lab equipment and furniture as part of the Company's initiative to monetize all remaining assets. As the estimated selling price less costs to sell are based primarily on unobservable inputs as they relate to the location and condition of the specific lab equipment and furniture, they are classified in Level 3 in the fair value heirarchy.