3. Balance Sheet Details

The following tables provide details of selected balance sheet accounts (in thousands):

	June 30, 2016			December 31, 2016

Accounts receivable	$	148,767		$	186,025
Less allowance for doubtful accounts	(7,051		)	(7,665		)

Total	$	141,716		$	178,360

	June 30, 2016		December 31, 2016

Raw materials	$	133,540	$	140,769
Work-in-process	47,460		67,935
Finished goods	92,288		75,084

Total	$	273,288	$	283,788

	Estimated
	Useful	June 30,			December 31,
	Lives	2016			2016
Land	N/A	$	14,498		$	14,498
Buildings, civil works and improvements	5 - 40 years	170,232			170,959
Leasehold improvements	1 - 12 years	9,015			9,619
Equipment and tooling	3 - 10 years	154,309			160,086
Furniture and fixtures	3 - 13 years	3,314			3,476
Computer equipment	3 - 5 years	17,902			18,621
Computer software	3 - 10 years	17,769			19,011
Construction in process	N/A	4,978			2,638

Total		392,017			398,908
Less accumulated depreciation and amortization		(208,903		)	(232,149		)

Property and equipment, net		$	183,114		$	166,759

Depreciation expense was approximately $13.0 million and $13.4 million for the three months ended December 31, 2015 and 2016, respectively, and approximately $26.0 million and $26.7 million for the six months ended December 31, 2015 and 2016, respectively.