Intangible Assets

The gross carrying amount and accumulated amortization of our intangible assets, other than goodwill, were as follows:



	September 30, 2015							December 31, 2014
	Gross Assets		Accumulated Amortization			Net		Gross Assets		Accumulated Amortization			Net
	(in thousands)
Core-developed technology	$	392,667	$	(357,007	)	$	35,660	$	405,434	$	(359,500	)	$	45,934
Customer contracts and relationships	242,627		(168,552		)	74,075		262,930		(172,755		)	90,175
Trademarks and trade names	64,808		(62,884		)	1,924		68,205		(64,905		)	3,300
Other	11,131		(11,023		)	108		11,579		(11,079		)	500
Total intangible assets	$	711,233	$	(599,466	)	$	111,767	$	748,148	$	(608,239	)	$	139,909

A summary of intangible asset activity is as follows:



	Nine Months Ended September 30,
	2015			2014
	(in thousands)
Beginning balance, intangible assets, gross	$	748,148		$	804,281
Intangible assets acquired	4,827			1,453
Intangible assets impaired	(497		)	—
Effect of change in exchange rates	(41,245		)	(35,742		)
Ending balance, intangible assets, gross	$	711,233		$	769,992

Intangible assets impaired includes purchased software licenses to be sold to others. This amount was expensed as part of cost of revenues in the Consolidated Statement of Operations.

Intangible assets acquired in 2015 are based on the preliminary purchase price allocation relating to our acquisition of Temetra. Refer to Note 5 for additional information regarding this acquisition. The following table reflects our preliminary allocation of purchase price for intangible assets acquired on August 26, 2015:



	Fair Value		Weighted Average Useful Life
	(in thousands)		(in years)
Identified intangible assets
Core-developed technology	$	4,378	7.0
Customer contracts and relationships	337		7.0
Trademarks and trade names	56		3.0
Other	56		2.0
Total identified intangible assets subject to amortization	$	4,827	6.9

Intangible assets of our international subsidiaries are recorded in their respective functional currency; therefore, the carrying amounts and accumulated amortization of intangible assets increase or decrease, with a corresponding change in accumulated OCI, due to changes in foreign currency exchange rates. Amortization expense is scheduled to decrease in future periods.

Estimated future annual amortization expense is as follows:



Years ending December 31,	Estimated Annual Amortization
	(in thousands)
2015 (amount remaining at September 30, 2015)	$	8,189
2016	25,566
2017	19,005
2018	13,271
2019	10,448
Beyond 2019	35,288
Total intangible assets subject to amortization	$	111,767