2. Balance Sheet Details

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

	June 30, 2015			December 31, 2015

Accounts receivable	$	184,419		$	162,326
Less allowance for doubtful accounts	(5,900		)	(4,527		)

Total	$	178,519		$	157,799

	June 30, 2015		December 31, 2015

Raw materials	$	131,373	$	162,927
Work-in-process	45,386		31,774
Finished goods	53,662		85,899

Total	$	230,421	$	280,600

	Estimated
	Useful	June 30,			December 31,
	Lives	2015			2015
Land	N/A	$	14,419		$	14,498
Buildings, civil works and improvements	5 - 40 years	170,373			169,179
Leasehold improvements	1 - 20 years	9,991			9,197
Equipment and tooling	3 - 10 years	152,518			144,115
Furniture and fixtures	3 - 13 years	3,475			3,417
Computer equipment	1 - 5 years	17,147			18,007
Computer software	3 - 10 years	16,612			16,357
Construction in process	N/A	6,365			4,004

Total		390,900			378,774
Less accumulated depreciation and amortization		(165,197		)	(186,807		)

Property and equipment, net		$	225,703		$	191,967

Depreciation expense was approximately $13.3 million and $13.0 million for the three months ended December 31, 2014 and 2015, respectively, and approximately $30.2 million and $26.0 million for the six months ended December 31, 2014 and 2015, respectively.