BALANCE SHEET COMPONENTS

Short-Term Investments

The amortized cost of our short-term investments approximates their fair value. As of July 31, 2017 and 2018, unrealized gains and losses from our short-term investments were not material. As of July 31, 2017 and 2018, securities that were in an unrealized loss position for more than 12 months were not material. Unrealized losses related to short-term investments are due to interest rate fluctuations, as opposed to credit quality. In addition, unless we need cash to support our current operations, we do not intend to sell and it is not likely that we would be required to sell these investments before recovery of their amortized cost basis, which may be at maturity. As a result, at July 31, 2017 and 2018, there were no other-than-temporary impairments for these investments.

The following table summarizes the estimated fair value of our investments in marketable debt securities by their contractual maturity dates:



	As of July 31, 2018
	(in thousands)
Due within one year	$	463,940
Due in one year through three years	164,388
Total	$	628,328

Property and Equipment, Net

Property and equipment, net consists of the following:



	Estimated Useful Life	As of July 31,
	Estimated Useful Life	2017			2018
	(in months)	(in thousands)
Computer, production, engineering, and other equipment	36	$	85,280		$	131,805
Demonstration units	12	46,387			53,547
Leasehold improvements	⁽¹⁾	10,562			19,916
Furniture and fixtures	60	4,744			7,636
Total property and equipment, gross		146,973			212,904
Less: Accumulated depreciation and amortization		(88,901		)	(127,793		)
Total property and equipment, net		$	58,072		$	85,111


(1)	Leasehold improvements are amortized over the shorter of the estimated useful lives of the improvements or the remaining lease term.

Depreciation expense related to our property and equipment was $26.4 million, $36.2 million and $43.7 million for the fiscal years ended July 31, 2016, 2017 and 2018, respectively.

Intangible Assets, Net

Intangible assets, net consists of the following:



	As of July 31,
	2017			2018
	(in thousands)
Indefinite-lived intangible asset:
In-process R&D ⁽¹⁾	$	16,100		$	—
Finite-lived intangible assets:
Developed technology ⁽¹⁾	7,300			47,500
Customer relationships	4,830			6,650
Total finite-lived intangible assets, gross	12,130			54,150
Total intangible assets, gross	28,230			54,150
Less:
Accumulated amortization of developed technology	(1,314		)	(6,956		)
Accumulated amortization of customer relationships	(915		)	(1,828		)
Total accumulated amortization	(2,229		)	(8,784		)
Intangible assets, net	$	26,001		$	45,366

(1)

We started amortizing in-process R&D during the first quarter of fiscal 2018, as the related technology was completed and made generally available in the first quarter of fiscal 2018. We are amortizing developed technology using the straight-line method over a useful life of five years. Based on the foregoing, the balance of in-process R&D is now presented as part of developed technology as of July 31, 2018.

The amortization expense related to our finite-lived intangible assets is being recognized in the consolidated statements of operations within product cost of revenue for developed technology and sales and marketing expense for customer relationships.

The changes in the net book value of intangible assets, net are as follows:



	As of July 31,
	2017			2018
	(in thousands)
Intangible assets, net—beginning balance	$	—		$	26,001
Acquired intangible assets	28,230			25,920
Amortization of intangible assets ⁽¹⁾	(2,229		)	(6,555		)
Intangible assets, net—ending balance	$	26,001		$	45,366


(1)	Represents amortization expense related to finite-lived intangible assets recognized during the year in the consolidated statements of operations, within product cost of revenue and sales and marketing expenses.

The estimated future amortization expense of our finite-lived intangible assets is as follows:



Fiscal Year Ending July 31:	Amount
	(in thousands)
2019	$	9,551
2020	9,511
2021	9,511
2022	8,314
2023	3,971
Thereafter	4,508
Total	$	45,366

Goodwill

The changes in the carrying amount of goodwill are as follows:



	Carrying Amount
	(in thousands)
Balance at July 31, 2016	$	—
Acquired in Calm Acquisition	4,819
Acquired in PernixData Acquisition	11,853
Balance at July 31, 2017	16,672
Acquired in Netsil Acquisition	53,085
Acquired in Minjar Acquisition	18,002
Balance at July 31, 2018	$	87,759

Other Assets—Non-Current

Other assets—non-current consists of the following:



	As of July 31,
	2017		2018
	(in thousands)
Other tax assets—non-current	$	—	$	30,927
Deferred tax assets—non-current	3,420		2,860
Other	4,229		4,068
Total other assets—non-current	$	7,649	$	37,855

Other tax assets—non-current as of July 31, 2018 represents a receivable associated with alternative minimum tax credit carryforwards which will be refundable as a result of the Tax Cuts and Jobs Act. For additional details, refer to Note 11.

Accrued Compensation and Benefits

Accrued compensation and benefits consists of the following:



	As of July 31,
	2017		2018
	(in thousands)
Contributions to ESPP withheld	$	14,371	$	21,931
Accrued commissions	20,388		21,660
Accrued bonus	7,342		12,129
Accrued vacation	6,286		10,548
Payroll taxes payable	3,434		9,563
Other	5,700		9,567
Total accrued compensation and benefits	$	57,521	$	85,398

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consists of the following:



	As of July 31,
	2017		2018
	(in thousands)
Income taxes payable ⁽¹⁾⁽²⁾	$	3,873	$	20,863
Accrued professional services	4,167		5,838
Other	1,667		4,981
Total accrued expenses and other current liabilities	$	9,707	$	31,682


(1)	Balance as of July 31, 2017 was adjusted to reflect the impact of the adoption of ASC 606 on income taxes. See Note 3 for a summary of adjustments.


(2)	The increase in income taxes payable during the fiscal year ended July 31, 2018 was due primarily to a payable related to the alternative minimum tax associated with the migration of certain intangible assets. For additional details, refer to Note 11.