The following table is a reconciliation of cash, cash equivalents and restricted cash reported within the accompanying condensed consolidated balance sheets that sum to the total of the same such amounts shown in the accompanying condensed consolidated statements of cash flows (in thousands):



	June 30, 2020		June 30, 2019
Cash and cash equivalents	$	800,182	$	944,414
Restricted cash included in Other assets	4,307		4,222
Total cash, cash equivalents and restricted cash	$	804,489	$	948,636

Restricted cash, which was included in "Other assets" on the accompanying condensed consolidated balance sheets as of June 30, 2020 and June 30, 2019, primarily consisted of $4.0 million pledged as collateral representing a security deposit required for a facility lease.



	June 30, 2020			December 31, 2019
Accounts receivable	$	385,005		$	398,147
Allowance for doubtful accounts	(501		)	(638		)
Product sales rebate and returns reserve	(1,279		)	(5,522		)
Accounts receivable, net	$	383,225		$	391,987



	June 30, 2020		December 31, 2019
Raw materials	$	171,346	$	96,712
Finished goods	155,651		147,113
Total inventories	$	326,997	$	243,825



	June 30, 2020		December 31, 2019
Prepaid income taxes	$	490	$	20,153
Inventory deposit	11,740		13,716
Other current assets	56,980		64,464
Other prepaid expenses and deposits	15,675		13,123
Total prepaid expenses and other current assets	$	84,885	$	111,456



	June 30, 2020			December 31, 2019
Equipment and machinery	$	65,950		$	64,748
Computer hardware and software	39,104			36,627
Leasehold improvements	31,217			31,235
Furniture and fixtures	3,733			3,774
Construction-in-process	488			265
Property and equipment, gross	140,492			136,649
Less: accumulated depreciation	(105,229		)	(97,376		)
Property and equipment, net	$	35,263		$	39,273

Depreciation expense was $5.1 million and $4.8 million for the three months ended June 30, 2020 and 2019, respectively, and $10.3 million and $9.5 million for the six months ended June 30, 2020 and 2019, respectively.



	June 30, 2020		December 31, 2019
Accrued payroll related costs	$	44,230	$	80,133
Accrued manufacturing costs	27,345		31,920
Accrued product development costs	10,620		11,410
Accrued professional fees	5,418		6,335
Accrued warranty costs	6,071		6,742
Accrued taxes	1,851		1,716
Other	4,535		1,993
Total accrued liabilities	$	100,070	$	140,249

The following table summarizes the activity related to our accrued liability for estimated future warranty costs (in thousands):



	Six Months Ended June 30,
	2020			2019
Warranty accrual, beginning of period	$	6,742		$	5,362
Liabilities accrued for warranties issued during the period	2,181			2,082
Warranty costs incurred during the period	(2,852		)	(2,370		)
Warranty accrual, end of period	$	6,071		$	5,074

The following table summarizes the balances of our contract assets included in "Prepaid and other current assets" on the accompanying condensed consolidated balance sheets (in thousands):



	Six Months Ended June 30,
	2020
Contract assets, beginning balance	$	25,565
Contract assets, ending balance	13,648



	Three Months Ended June 30,						Six Months Ended June 30,
	2020			2019			2020			2019
Contract liabilities, beginning balance	$	64,325		$	37,314		$	61,050		$	32,595
Less: Revenue recognized from beginning balance	(5,735		)	(3,552		)	(11,722		)	(6,766		)
Less: Beginning balance reclassified to deferred revenue	(2,757		)	(1,593		)	(2,226		)	(1,205		)
Add: Contract liabilities recognized	11,435			9,857			20,166			17,402
Contract liabilities, ending balance	$	67,268		$	42,026		$	67,268		$	42,026

As of June 30, 2020 and December 31, 2019, $28.6 million and $23.4 million of our contract liabilities, respectively, were included in "Other current liabilities" with the remaining balances included in "Other long-term liabilities" on the accompanying condensed consolidated balance sheets.

Deferred revenue is comprised primarily of unearned revenue related to multi-year post contract support, or PCS, contracts, services and product deferrals related to acceptance clauses. The following table summarizes the activity related to our deferred revenue (in thousands):



	Three Months Ended June 30,						Six Months Ended June 30,
	2020			2019			2020			2019
Deferred revenue, beginning balance	$	596,775		$	536,471		$	575,288		$	587,227
Less: Revenue recognized from beginning balance	(104,480		)	(119,542		)	(178,264		)	(253,616		)
Add: Deferral of revenue in current period, excluding amounts recognized during the period	85,216			85,289			180,487			168,607
Deferred revenue, ending balance	$	577,511		$	502,218		$	577,511		$	502,218

Revenue from remaining performance obligations represents contracted revenue that has not yet been recognized, and consists of contract liabilities and deferred revenue that will be recognized as revenue in future periods. As of June 30, 2020, approximately $687.7 million of revenue is expected to be recognized from remaining performance obligations. We expect to recognize revenue on approximately 81% of these remaining performance obligations over the next two years and 19% during the third to the fifth year.



	Three Months Ended June 30,					Six Months Ended June 30,
	2020			2019		2020		2019
Interest income	$	8,668		$	13,107	$	20,330	$	25,005
Gain on investment in privately-held companies	—			—		—		1,150
Other income (expense), net	(412		)	704		83		(11		)
Total	$	8,256		$	13,811	$	20,413	$	26,144