5. Patents and Licenses

6 Months Ended

Jun. 30, 2018

Patents And Licenses

Patents and Licenses

Purchased patents and license fees paid for the use of other entities’ patents are amortized over the useful life of the patent or license. The following tables provide information regarding patents and licenses (dollars in thousands):

June 30, 2018						December 31, 2017
Weighted Average Original Life (years)		Gross Carrying Amount		Accumulated Amortization		Weighted Average Original Life (years)		Gross Carrying Amount		Accumulated Amortization
	15.67	$	13,840	$	12,122		15.67	$	13,840	$	12,062

Aggregate amortization expense for patents and licenses was $30,000 for the three months ended June 30, 2018 and 2017 and $60,000 and $92,000 for the six months ended June 30, 2018 and 2017, respectively.

Estimated future amortization expense for each of the years set forth below ending December 31 is as follows (in thousands):

2019	$	119
2020	$	119
2021	$	119
2022	$	117
2023	$	113