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):



	March 31, 2020		March 31, 2019
Cash and cash equivalents	$	761,333	$	809,491
Restricted cash included in other assets	4,307		4,218
Total cash, cash equivalents and restricted cash	$	765,640	$	813,709

Restricted cash included in other assets as of March 31, 2020 and March 31, 2019 primarily included $4.0 million pledged as collateral representing a security deposit required for a facility lease.



	March 31, 2020			December 31, 2019
Accounts receivable	$	358,220		$	398,147
Allowance for doubtful accounts	(424		)	(638		)
Product sales rebate and returns reserve	(5,637		)	(5,522		)
Accounts receivable, net	$	352,159		$	391,987



	March 31, 2020		December 31, 2019
Raw materials	$	130,357	$	96,712
Finished goods	131,441		147,113
Total inventories	$	261,798	$	243,825



	March 31, 2020		December 31, 2019
Prepaid income taxes	$	8,706	$	20,153
Inventory deposit	12,802		13,716
Other current assets	50,373		64,464
Other prepaid expenses and deposits	14,068		13,123
Total prepaid expenses and other current assets	$	85,949	$	111,456



	March 31, 2020			December 31, 2019
Equipment and machinery	$	63,461		$	64,748
Computer hardware and software	39,061			36,627
Leasehold improvements	31,150			31,235
Furniture and fixtures	3,713			3,774
Construction-in-process	405			265
Property and equipment, gross	137,790			136,649
Less: accumulated depreciation	(99,984		)	(97,376		)
Property and equipment, net	$	37,806		$	39,273

Depreciation expense was $5.2 million and $4.7 million for the three months ended March 31, 2020 and 2019, respectively.



	March 31, 2020		December 31, 2019
Accrued payroll related costs	$	43,842	$	80,133
Accrued manufacturing costs	30,998		31,920
Accrued product development costs	7,162		11,410
Accrued professional fees	5,160		6,335
Accrued warranty costs	6,341		6,742
Accrued taxes	1,843		1,716
Other	5,097		1,993
Total accrued liabilities	$	100,443	$	140,249

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



	Three Months Ended March 31,
	2020			2019
Warranty accrual, beginning of period	$	6,742		$	5,362
Liabilities accrued for warranties issued during the period	1,070			932
Warranty costs incurred during the period	(1,471		)	(1,168		)
Warranty accrual, end of period	$	6,341		$	5,126



	Three Months Ended March 31,
	2020		2019
Contract assets, beginning balance	$	25,565	$	6,341
Contract assets, ending balance	9,636		5,699



	Three Months Ended March 31,
	2020			2019
Contract liabilities, beginning balance	$	61,050		$	32,595
Less: Revenue recognized from beginning balance	(4,847		)	(2,826		)
Less: Beginning balance reclassified to deferred revenue	(2,433		)	(1,259		)
Add: Contract liabilities recognized	10,555			8,804
Contract liabilities, ending balance	$	64,325		$	37,314

As of March 31, 2020 and December 31, 2019, $26.3 million and $23.4 million of our contract liabilities, respectively, was included in “Other current liabilities” with the remaining balances included in “Other long-term liabilities”.

Deferred revenue is comprised mainly of unearned revenue related to multi-year 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 March 31,
	2020			2019
Deferred revenue, beginning balance	$	575,288		$	587,227
Less: Revenue recognized from beginning balance	(100,377		)	(190,597		)
Add: Deferral of revenue in current period, excluding amounts recognized during the period	121,864			139,841
Deferred revenue, ending balance	$	596,775		$	536,471

Revenue from remaining performance obligations represents contracted revenue that has not yet been recognized, which includes contract liabilities and deferred revenue that will be recognized as revenue in future periods. As of March 31, 2020, approximately $716.5 million of revenue is expected to be recognized from remaining performance obligations. We expect to recognize revenue on approximately 80% of these remaining performance obligations over the next two years and 20% during the third to the fifth year.



	Three Months Ended March 31,
	2020		2019
Interest income	$	11,662	$	11,898
Gain (loss) on investment in privately-held companies	—		1,150
Other income (expense), net	495		(715		)
Total	$	12,157	$	12,333