Property and Equipment

12 Months Ended

Dec. 31, 2017

Property Plant And Equipment [Abstract]

Property and Equipment

5. Property and Equipment

Property and equipment and related accumulated depreciation and amortization are as follows (in thousands):

	2017			2016
Lab equipment	$	36,533		$	34,727
Computer equipment		11,808			11,534
Software		10,694			5,429
Furniture and office equipment		3,959			3,638
Leasehold improvements		26,968			24,730
Construction in progress		7,523			4,512
Total cost		97,485			84,570
Less: accumulated depreciation and amortization		(56,366	)		(43,084	)
Total property and equipment, net	$	41,119		$	41,486

Depreciation and amortization expense for the years ended December 31, 2017, 2016, and 2015 was $18,517,000, $15,949,000, and $10,600,000, respectively. The Company classifies capitalized internal-use software in lab equipment, computer equipment and software based on its intended use. Depreciation expense related to all capitalized internal-use software for the years ended December 31, 2017, 2016, and 2015 was $1,057,000, $213,000 and $238,000, respectively. The remaining unamortized capitalized internal-use software costs at December 31, 2017 and 2016 was $4,172,000 and $1,052,000, respectively.