Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2019

Commitments and Contingencies

Schedule of changes in product warranty reserves

	December 31,
	2019		2018		2017
		(in thousands)
Balance, beginning of the year	$	7,852	$	6,532	$	4,217
Warranties issued		5,865		6,737		5,817
Addition from Ultratech acquisition		—		—		1,889
Consumption of reserves		(6,242)		(6,573)		(6,330)
Changes in estimate		(408)		1,156		939
Balance, end of the year	$	7,067	$	7,852	$	6,532

Schedule of maturities of lease liabilities 2019

	Operating
	Leases
	(in thousands)
Payments due by period:
2020	$	4,932
2021		5,020
2022		4,428
2023		1,133
2024		551
Thereafter		—
Total future minimum lease payments		16,064
Less: Imputed interest		(1,568)
Total	$	14,496
Reported as of December 31, 2019
Other current liabilities	$	4,196
Operating lease liabilities		10,300
Total	$	14,496

Schedule of minimum lease commitments 2018

Minimum lease commitments at December 31, 2018 for property and equipment under operating lease agreements (exclusive of renewal options) were as follows:

	Operating
	Leases
	(in thousands)
Payments due by period:
2019	$	5,143
2020		5,056
2021		2,432
2022		1,812
2023		1,066
Thereafter		548
Total	$	16,057

Schedule of customers who accounted for more than 10% of our aggregate accounts receivable or net sales

	Accounts Receivable				Net Sales
	December 31,				For the Year Ended December 31,
Customer	2019		2018		2019		2018		2017
Customer A	16	%	22	%	11	%	*		*
Customer B	21	%	*		*		*		*
Customer C	*		*		*		12	%	*
Customer D	*		*		*		*		21	%

* Less than 10% of aggregate accounts receivable or net sales