11. Other Balance Sheet Information

The following is a summary of accounts receivable at December 31, 2012 and September 30, 2012 (in thousands):


	December 31, 2012		September 30, 2012
Accounts receivable	$	64,793	$	79,706
Less allowances		961		851

	$	63,832	$	78,855

The following is a summary of inventories at December 31, 2012 and September 30, 2012 (in thousands):


	December 31, 2012		September 30, 2012
Inventories
Raw materials and purchased parts	$	61,012	$	64,732
Work-in-process		25,525		20,800
Finished goods		18,586		17,453

	$	105,123	$	102,985

The Company provides for the estimated cost of product warranties, primarily from historical information, at the time product revenue is recognized and retrofit accruals 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. Product warranty and retrofit activity on a gross basis for the three months ended December 31, 2012 and 2011 is as follows (in thousands):

Activity — Three Months Ended December 31, 2012


Balance September 30, 2012		Adjustments for acquisitions and divestitures		Accruals		Costs incurred			Balance December 31, 2012
$	7,329	$	962	$	2,363	$	(2,930	)	$	7,724

Activity — Three Months Ended December 31, 2011


Balance September 30, 2011		Adjustments for acquisitions and divestitures		Accruals		Costs incurred			Balance December 31, 2011
$	7,438	$	7	$	3,518	$	(3,670	)	$	7,293