PROPERTY, PLANT, AND EQUIPMENT

3 Months Ended

Mar. 31, 2020

Property, Plant and Equipment [Abstract]

PROPERTY, PLANT, AND EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT

The estimated useful lives of property, plant and equipment are as follows:

(In thousands)	Estimated Useful Life	March 31, 2020		December 31, 2019
Property, plant and equipment	​	​		​
Land	n/a	$	4,466	$	4,466
Leasehold and building improvements	(1)	109,737		80,352
Land improvements	15 years	1,766		1,766
Buildings	30 years	165,509		112,815
Computer equipment and computer software	3 years	68,830		65,323
Laboratory equipment	3 - 10 years	120,362		104,008
Furniture and fixtures	3 - 10 years	20,886		14,539
Assets under construction	n/a	67,305		149,687
Property, plant and equipment, at cost	​	558,861		532,956
Accumulated depreciation	​	(93,385)		(77,631)
Property, plant and equipment, net	​	$	465,476	$	455,325

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(1)Lesser of remaining lease term, building life, or estimated useful life.

Depreciation expense for the three months ended March 31, 2020 and 2019 was $15.8 million and $6.3 million, respectively.

At March 31, 2020, the Company had $67.3 million of assets under construction which consisted of $17.0 million in laboratory equipment under construction, $44.3 million of building and leasehold improvements, $5.7 million in capitalized costs related to software projects, and $0.3 million related to furniture and fixtures. Depreciation will begin on these assets once they are placed into service. The Company expects to incur an additional $4.8 million to complete the laboratory equipment, $7.3 million to complete the building projects and leasehold improvements, $5.2 million to complete the software projects, and minimal costs to complete the furniture and fixtures. These projects are expected to be completed throughout 2020 and 2021.