Property, Plant, and Equipment, Net

Property, plant, and equipment, net were as follows:



	December 31,
(In thousands)	2018			2017
Buildings	$	18,799		$	20,806
Machinery and equipment	87,700			82,188
Tooling	29,575			33,622
Leasehold and building improvements	34,486			31,158
Software	25,406			18,240
Furniture and fixtures	2,572			5,620
Computer equipment	8,551			7,154
	207,089			198,788
Accumulated depreciation	(116,805		)	(102,323		)
	90,284			96,465
Construction in progress	5,556			14,497
Total property, plant, and equipment, net	$	95,840		$	110,962

Depreciation expense, including tooling depreciation which is recorded in cost of goods sold, was $26.4 million, $24.4 million and $20.7 million for the years ended December 31, 2018, 2017, and 2016, respectively.

The net book value of property, plant, and equipment located within the PRC was $76.4 million and $93.6 million on December 31, 2018 and 2017, respectively.

During the year ended December 31, 2018, we incurred $2.9 million in impairment on tooling and equipment as a result of the transition of manufacturing operations between our China-based manufacturing facilities following the closure of our Guangzhou factory, which was sold in 2018. We incurred an additional $2.0 million of impairment on factory equipment during the year ended December 31, 2018 as a result of the transition of certain manufacturing operations out of China in response to tariffs enacted in the U.S. in 2018 on certain products manufactured in China and imported into the U.S. These impairment charges, aggregating to $4.9 million, are recorded within cost of goods sold for the year ended December 31, 2018. During the fourth quarter of 2017, we performed an impairment analysis over our factory assets in China, which was triggered primarily by the transition of a number of our customers to next generation products. Based on our forecasted future production, we determined that the realizable value of certain tooling and equipment was less than net book value. Accordingly, we recorded an impairment charge of $4.1 million, of which $3.8 million was recorded in cost of goods sold and the remaining $0.3 million was recorded in selling, general and administrative expenses, during the year ended December 31, 2017.

Construction in progress was as follows:



	December 31,
(In thousands)	2018		2017
Buildings	$	275	$	—
Machinery and equipment	2,444		3,884
Tooling	1,581		3,697
Leasehold and building improvements	675		1,014
Software	352		5,714
Other	229		188
Total construction in progress	$	5,556	$	14,497

We expect that most of the assets under construction will be placed into service during the first six months of 2019. We will begin to depreciate the cost of these assets under construction once they are placed into service.