10. Other Balance Sheet Information

The following is a summary of accounts receivable at June 30, 2018 and September 30, 2017 (in thousands):


	June 30,		September 30,
	2018		2017
Accounts receivable	$	157,872	$	122,868
Less allowance for doubtful accounts		(1,142)		(1,959)
Less allowance for sales returns		(52)		(81)
Accounts receivable, net	$	156,678	$	120,828

The following is a summary of inventories at June 30, 2018 and September 30, 2017 (in thousands):


	June 30,		September 30,
	2018		2017
Inventories
Raw materials and purchased parts	$	83,603	$	73,819
Work-in-process		21,699		10,548
Finished goods		26,996		22,028
Total inventories	$	132,298	$	106,395

Reserves for excess and obsolete inventory were $21.0 million and $23.5 million, respectively, at June 30, 2018 and September 30, 2017.

At June 30, 2018 and September 30, 2017, the Company had cumulative capitalized direct costs of $5.5 million and $4.7 million, respectively, associated with the development of software for its internal use which are included within "Property, plant and equipment, net" in the accompanying unaudited Consolidated Balance Sheets. During the nine months ended June 30, 2018, the Company capitalized direct costs of $0.8 million associated with the development of software for its internal use.

The Company establishes reserves for estimated costs of product warranties based on historical information. Product warranty reserves are recorded at the time product revenue is recognized, and retrofit accruals are recorded at the time retrofit programs are established. The Company’s warranty obligation is affected by product failure rates, utilization levels, material usage, service delivery costs incurred in correcting a product failure and supplier warranties on parts delivered to the Company.

The following is a summary of product warranty and retrofit activity on a gross basis for the three and nine months ended June 30, 2018 and 2017 (in thousands):


Activity -Three Months Ended June 30, 2018
Balance						Balance
March 31,						June 30,
2018		Accruals		Costs Incurred		2018
$	8,289	$	1,895	$	(1,425)	$	8,759


Activity -Three Months Ended June 30, 2017
Balance						Balance
March 31,						June 30,
2017		Accruals		Costs Incurred		2017
$	7,073	$	2,440	$	(1,867)	$	7,646


Activity -Nine Months Ended June 30, 2018
Balance						Balance
September 30,						June 30,
2017		Accruals		Costs Incurred		2018
$	8,054	$	6,304	$	(5,599)	$	8,759


Activity -Nine Months Ended June 30, 2017
Balance						Balance
September 30,						June 30,
2016		Accruals		Costs Incurred		2017
$	6,324	$	7,656	$	(6,334)	$	7,646