Intangible Assets

Intangible assets with finite lives are as follows:



	As of October 31, 2017
	Weighted Average Amortization Period	Gross Carrying Amount		Accumulated Amortization	Net Carrying Amount
Customer relationships	20.3	$	249,831,000	45,280,000	$	204,551,000
Technologies	12.3	82,370,000		50,064,000	32,306,000
Trademarks and other	16.4	28,894,000		9,149,000	19,745,000
Total		$	361,095,000	104,493,000	$	256,602,000



	As of July 31, 2017
	Weighted Average Amortization Period	Gross Carrying Amount		Accumulated Amortization	Net Carrying Amount
Customer relationships	20.3	$	249,831,000	41,923,000	$	207,908,000
Technologies	12.3	82,370,000		48,623,000	33,747,000
Trademarks and other	16.4	28,894,000		8,678,000	20,216,000
Total		$	361,095,000	99,224,000	$	261,871,000

The weighted average amortization period in the above table excludes fully amortized intangible assets.

Amortization expense for the three months ended October 31, 2017 and 2016 was $5,269,000 and $6,055,000, respectively.

The estimated amortization expense consists of the following for the fiscal years ending July 31,:



2018	$	21,075,000
2019	17,155,000
2020	17,155,000
2021	16,196,000
2022	14,955,000

We review net intangible assets with finite lives for impairment when an event occurs indicating the potential for impairment. No such event has occurred during the three months ended October 31, 2017. We believe that the carrying values of our net intangible assets were recoverable as of October 31, 2017. Any impairment charges that we may record in the future could be material to our results of operation and financial condition.