Intangible Assets

Intangible assets with finite lives are as follows:



	As of January 31, 2020
	Weighted Average Amortization Period	Gross Carrying Amount		Accumulated Amortization	Net Carrying Amount
Customer relationships	20.5	$	282,934,000	72,909,000	$	210,025,000
Technologies	13.7	97,649,000		62,377,000	35,272,000
Trademarks and other	16.6	32,726,000		13,768,000	18,958,000
Total		$	413,309,000	149,054,000	$	264,255,000



	As of July 31, 2019
	Weighted Average Amortization Period	Gross Carrying Amount		Accumulated Amortization	Net Carrying Amount
Customer relationships	20.5	$	276,834,000	66,484,000	$	210,350,000
Technologies	12.7	92,649,000		59,522,000	33,127,000
Trademarks and other	16.7	31,026,000		12,613,000	18,413,000
Total		$	400,509,000	138,619,000	$	261,890,000

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

Amortization expense for the three months ended January 31, 2020 and 2019 was $5,229,000 and $4,288,000, respectively. Amortization expense for the six months ended January 31, 2020 and 2019 was $10,435,000 and $8,577,000, respectively.

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



2020	$	21,557,000
2021	20,770,000
2022	19,091,000
2023	19,091,000
2024	18,399,000

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 six months ended January 31, 2020. We believe that the carrying values of our net intangible assets were recoverable as of January 31, 2020. Any impairment charges that we may record in the future could be material to our results of operations and financial condition.