5. Goodwill and Other Intangibles

Goodwill consists of the following:

 

		As of December 31,
		2015				2014
		(in thousands)
Balance at beginning of year		$	17,281			$	15,031
Additions for acquisitions			742				2,555
Effects of currency exchange			(234	)			(305	)
Balance at end of year		$	17,789			$	17,281

 

Other intangibles consist of the following:

 

		2015												2014
		Gross Carrying Value				Accumulated Amortization				Net Carrying Value of Intangible Assets				Gross Carrying Value				Accumulated Amortization				Net Carrying Value of Intangible Assets
		(in thousands)
Product technology		$	7,113			$	3,247			$	3,866			$	7,134			$	2,777			$	4,357
Trademarks and licenses			1,560				1,230				330				1,557				1,074				483
Customer relationships			3,801				2,143				1,658				3,694				1,781				1,913
Other intangible assets			1,297				815				482				1,084				680				404
Total identifiable intangible assets		$	13,771			$	7,435			$	6,336			$	13,469			$	6,312			$	7,157

These assets are being amortized over useful lives ranging from 1 to 13 years. The weighted-average amortization period for these intangibles as of December 31, 2015, is 6.0 years. Amortization expense is included in general and administrative expense and is as follows:

 

		Year ended December 31,
		2015				2014				2013
						(in thousands)
Amortization expense		$	1,513			$	1,539			$	1,220

Estimated amortization expense for each of the five succeeding fiscal years, based upon the intangible assets at December 31, 2015, is as follows:

 

		Year ended December 31,
		2016				2017				2018				2019				2020
										(in thousands)
Amortization expense		$	1,469			$	1,212			$	1,025			$	838			$	585