GOODWILL AND OTHER INTANGIBLE ASSETS

The following table summarizes the changes in our goodwill:



Balance at December 31, 2018	$	111,387
Goodwill recognized upon acquisition	4,826
Adjustment to goodwill associated with acquisitions	(176		)
Foreign exchange adjustment to goodwill	(80		)
Balance at September 30, 2019	$	115,957

There has been no impairment of goodwill for the periods presented.

The gross carrying amount and accumulated amortization of our intangible assets as of September 30, 2019 and December 31, 2018 are as follows:



		September 30, 2019
Intangible Assets	Weighted Average Amortization Period (in Years)	Gross		Accumulated Amortization			Net

Developed Technology	6.0	$	14,744	$	(8,862	)	$	5,882
Customer Relationships	8.8	90,102		(27,640		)	62,462
Reseller Relationships	7.0	853		(853		)	0
Trade Names	12.0	5,299		(1,564		)	3,735
Noncompete Agreements	5.2	1,032		(639		)	393
	8.5	$	112,030	$	(39,558	)	$	72,472



		December 31, 2018
Intangible Assets	Weighted Average Amortization Period (in Years)	Gross		Accumulated Amortization			Net

Developed Technology	6.0	$	14,805	$	(7,065	)	$	7,740
Customer Relationships	8.5	85,094		(20,601		)	64,493
Reseller Relationships	7.0	853		(853		)	—
Trade Names	12.2	5,187		(1,241		)	3,946
Noncompete Agreements	5.2	1,032		(451		)	581
	8.3	$	106,971	$	(30,211	)	$	76,760

We record amortization expenses using the straight-line method over the estimated useful lives of the intangible assets, as noted above. Amortization expenses recorded in Operating Expenses were $2,375 and $2,447, for the three months ended September 30, 2019 and 2018, respectively. Amortization expenses recorded in Cost of Sales were $587 and $437 for the three months ended September 30, 2019 and 2018, respectively. Amortization expenses recorded in Operating Expenses were $7,918 and $6,038 for the nine months ended September 30, 2019 and 2018, respectively. Amortization expenses recorded in Cost of Sales were and $1,461 and $1,171 for the nine months ended September 30, 2019 and 2018, respectively.

The following table summarizes the future estimated amortization expense relating to our intangible assets as of September 30, 2019:



Calendar Years
2019 (October to December)	$	2,952
2020	11,474
2021	10,983
2022	10,354
2023	9,140
2024	8,821
Thereafter	18,748
	$	72,472