(5) Intangible Assets

Intangible assets other than goodwill at March 31, 2013 and December 31, 2012 were as follows:



	2013							2012
(in thousands)	Gross		Accumulated Amortization			Net		Gross		Accumulated Amortization			Net		Useful Life (in years)
Intangible assets with finite lives:
Licenses	$	5,875	$	(5,875	)	$	—	$	5,875	$	(5,875	)	$	—
Patent costs		27,398		(14,100	)		13,298		27,635		(14,047	)		13,588	6 - 7
Acquired technology		26,174		(12,190	)		13,984		26,262		(11,852	)		14,410	5 - 10
Internally developed software		17,847		(11,783	)		6,064		17,847		(11,424	)		6,423	5
Customer relationships		70,618		(9,483	)		61,135		60,329		(7,754	)		52,575	5 - 13
Non-compete agreements		14,294		(4,366	)		9,928		14,051		(3,836	)		10,215	3 - 11
Trade names		7,929		(1,032	)		6,897		5,814		(723	)		5,091	2 - 10
Other		11,424		(3,348	)		8,076		6,356		(3,051	)		3,305	<1 - 7
Intangibles with indefinite lives:
Trademarks		2,110		—			2,110		2,770		—			2,770	N/A
Total intangible assets	$	183,669	$	(62,177	)	$	121,492	$	166,939	$	(58,562	)	$	108,377	<1 - 13

For the three months ended March 31, 2013 and 2012, the Company capitalized $177 and $231, respectively, of costs incurred to acquire, develop and extend patents in the United States and various other countries.

Amortization expense for intangible assets for the quarter ended March 31, 2013 was $3,812 compared to $3,419 for the quarter ended March 31, 2012.

Annual amortization expense for intangible assets for 2013, 2014, 2015, 2016 and 2017 is expected to be $16,373, $16,841 $15,263, $13,261 and $12,006, respectively.