PROPERTY, PLANT AND EQUIPMENT

9 Months Ended

Sep. 30, 2021

Property, Plant and Equipment [Abstract]

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


(In thousands)	Estimated Useful Life	September 30, 2021		December 31, 2020
Property, plant and equipment
Land	n/a	$	4,466	$	4,466
Leasehold and building improvements	(1)	142,025		117,865
Land improvements	15 years	4,894		4,864
Buildings	30 - 40 years	201,040		200,980
Computer equipment and computer software	3 years	99,889		75,417
Laboratory equipment	3 - 10 years	175,393		142,110
Furniture and fixtures	3 - 10 years	27,593		24,968
Assets under construction	n/a	64,187		18,854
Property, plant and equipment, at cost		719,487		589,524
Accumulated depreciation		(195,287)		(137,538)
Property, plant and equipment, net		$	524,200	$	451,986

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

Depreciation expense for the three months ended September 30, 2021 and 2020 was $22.3 million and $19.7 million, respectively. Depreciation expense for the nine months ended September 30, 2021 and 2020 was $64.3 million and $53.3 million, respectively.

At September 30, 2021, the Company had $64.2 million of assets under construction which consisted of $11.8 million in laboratory equipment, $40.6 million related to building and leasehold improvements, $11.6 million in capitalized costs related to software projects, and $0.2 million related to land improvements. Depreciation will begin on these assets once they are placed into service upon completion between 2021 and 2023.