3. Balance Sheet Details

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

	June 30, 2017			March 31, 2018

Accounts receivable	$	216,089		$	226,217
Less allowance for doubtful accounts	(9,563		)	(9,537		)

Accounts receivable, net	$	206,526		$	216,680

	June 30, 2017		March 31, 2018

Raw materials	$	129,645	$	157,434
Work-in-process	65,454		85,273
Finished goods	53,411		61,586

Inventories	$	248,510	$	304,293

	June 30,			March 31,
	2017			2018
Land, buildings, civil works and improvements	$	171,335		$	73,893
Leasehold improvements	9,025			9,317
Equipment and tooling	166,991			115,220
Furniture and fixtures	3,371			3,429
Computer equipment	17,991			18,801
Computer software	17,303			19,146
Computer software implementation in process	2,590			3,344
Construction in process	1,049			1,239

Total	389,655			244,389
Less accumulated depreciation and amortization	(248,116		)	(130,722		)

Property and equipment, net	$	141,539		$	113,667

In September 2017, we purchased the AS&E facility in Billerica, MA for $19.8 million. Depreciation expense was approximately $13.3 million and $5.4 million for the three months ended March 31, 2017 and 2018, respectively, and approximately $39.9 million and $38.4 million for the nine months ended March 31, 2017 and 2018, respectively.

In January 2018, we entered into a new two-year agreement with the Mexican government to continue providing security screening services. Upon inception of the new contract, we transferred certain fixed assets to the customer, and this remaining cost to obtain the contract is amortized on a straightline basis as corresponding revenues are recognized. As of March 31, 2018, $14.7 million and $11.6 million are recorded within Prepaid expenses and other current assets and Other assets, respectively.