Composition of Certain Financial Statement Captions

The following tables present detailed information from our consolidated balance sheets as of September 28, 2018 and September 29, 2017 (amounts displayed in thousands, except as otherwise noted).

Accounts Receivable



Accounts Receivable, Net	September 28, 2018			September 29, 2017
Trade accounts receivable	$	101,945		$	62,305
Accounts receivable from patent administration program licensees	40,558			14,412
Accounts receivable, gross	142,503			76,717
Less: allowance for doubtful accounts	(5,352		)	(2,967		)
Total	$	137,151		$	73,750



Allowance for Doubtful Accounts	Beginning Balance		Charged to G&A		Deductions			Ending Balance
For fiscal year ended:
September 30, 2016	$	1,542	$	1,017	$	(189	)	$	2,370
September 29, 2017	2,370		924		(327		)	2,967
September 28, 2018	2,967		2,507		(122		)	5,352

Inventories



Inventories	September 28, 2018		September 29, 2017
Raw materials	$	6,095	$	6,812
Work in process	4,044		4,954
Finished goods	16,067		13,285
Total	$	26,206	$	25,051

Inventories are stated at the lower of cost and net realizable value. Inventory with a consumption period expected to exceed twelve months is recorded within other non-current assets in our consolidated balance sheets. We have included $2.6 million and $1.8 million of raw materials inventory within other non-current assets in our consolidated balance sheets as of September 28, 2018 and September 29, 2017, respectively. Based on anticipated inventory consumption rates, and aside from existing write-downs due to excess inventory, we do not believe that material risk of obsolescence exists prior to ultimate sale.

Prepaid Expenses And Other Current Assets



Prepaid Expenses And Other Current Assets	September 28, 2018		September 29, 2017
Prepaid expenses	$	18,508	$	16,681
Other current assets	14,265		11,383
Income tax receivable	2,436		2,444
Total	$	35,209	$	30,508

Accrued Liabilities



Accrued Liabilities	September 28, 2018		September 29, 2017
Accrued royalties	$	2,430	$	2,274
Amounts payable to patent administration program partners	53,942		49,141
Accrued compensation and benefits	84,491		92,277
Accrued professional fees	9,749		5,530
Unpaid PP&E additions	13,956		10,096
Other accrued liabilities	59,026		47,716
Total	$	223,594	$	207,034

Other Non-Current Liabilities



Other Non-Current Liabilities	September 28, 2018		September 29, 2017
Supplemental retirement plan obligations	$	3,388	$	2,928
Non-current tax liabilities	129,253		91,013
Other liabilities	18,319		13,573
Total	$	150,960	$	107,514

Refer to Note 10 “Income Taxes” for additional information related to tax liabilities.