Goodwill and Other Intangible Assets

12 Months Ended

Dec. 31, 2015

Goodwill and Intangible Assets Disclosure [Abstract]

The changes in carrying amount of goodwill for the years ended December 31, 2015 and 2014 were as follows:



	Carrying Value
	(in thousands)
Goodwill - December 31, 2013	$	159,342
Goodwill - December 31, 2014	159,342
Additions	12,745
Goodwill - December 31, 2015	$	172,087

Our acquisition-related intangible assets as of December 31, 2015 and 2014 were as follows:



	December 31, 2015
	Gross Carrying Value		Accumulated Amortization			Net Carrying Amount
	(in thousands)
Trade name and trademarks	$	4,060	$	(3,096	)	$	964
Technology	36,290		(19,552		)	16,738
Customer relationships	21,030		(9,450		)	11,580
Assembled workforce	$	962	$	(70	)	892
Total other intangible assets	$	62,342	$	(32,168	)	$	30,174



	December 31, 2014
	Gross Carrying Value		Accumulated Amortization			Net Carrying Amount
	(in thousands)
Trade name and trademarks	$	4,060	$	(2,296	)	$	1,764
Technology	36,290		(13,669		)	22,621
Customer relationships	21,030		(7,100		)	13,930
Total other intangible assets	$	61,380	$	(23,065	)	$	38,315

The estimated useful lives of our acquired trade names and trademarks range from one to five years, our acquired technology has estimated useful lives of seven years and our acquired customer relationships have estimated useful lives ranging from one year to ten years.

In the year ended December 31, 2015 we acquired two assembled workforces through two asset acquisitions for a total of $1.0 million. Should the employees remain employed through a period of up to 2 years following each acquisition we will be required to make additional payments totaling $1.2 million. The estimated useful lives of our assembled workforces is two years.

As of December 31, 2015, the weighted-average remaining useful lives of all acquisition-related intangible assets was 3.7 years. Amortization expense for the years ended December 31, 2015, 2014, and 2013 was $9.1 million, $8.9 million, and $7.9 million, respectively.

Estimated future amortization of acquisition-related intangible asset for future periods is as follows:



Years Ending December 31,	(in thousands)
2016	$	9,977
2017	7,639
2018	7,064
2019	2,518
2020	1,350
Thereafter	1,626
	$	30,174