Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2013

Intangible assets subject to amortization

Intangible assets subject to amortization at December 31, 2013 consisted of the following:

(In thousands)	Gross Carrying Amount		Accumulated Amortization		Net

Customer contracts	$	59,574	$	51,512	$	8,062
Acquired technology		29,431		25,589		3,842
Patents		24,547		15,081		9,466
Distributor and provider networks		8,709		7,190		1,519
Perpetual license to survey-based data		30,000		3,986		26,014
Other		5,077		3,867		1,210
Total	$	157,338	$	107,225	$	50,113

Intangible assets subject to amortization at December 31, 2012 consisted of the following:

(In thousands)	Gross Carrying Amount		Accumulated Amortization		Net

Customer contracts	$	59,305	$	44,571	$	14,734
Acquired technology		29,287		24,299		4,988
Patents		24,337		12,723		11,614
Distributor and provider networks		8,709		6,669		2,040
Perpetual license to survey-based data		29,000		2,708		26,292
Other		5,097		3,586		1,511
Total	$	155,735	$	94,556	$	61,179

Estimated future amortization expense

Intangible assets subject to amortization are being amortized over estimated useful lives ranging from two to 25 years. Total amortization expense for the years ended December 31, 2013, 2012, and 2011, was $12.7 million, $12.6 million, and $13.4 million, respectively. The following table summarizes the estimated amortization expense for each of the next five years and thereafter:

(In thousands)
Year ending December 31,
2014	$	11,170
2015		6,783
2016		5,003
2017		3,343
2018		3,307
2019 and thereafter		20,507
Total	$	50,113