3. Patents and Licenses

12 Months Ended

Dec. 31, 2016

Goodwill and Intangible Assets Disclosure [Abstract]

Patents and Licenses

Purchased patents and licenses 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):

December 31, 2016						December 31, 2015
Weighted Average Original Life (years)		Gross Carrying Amount		Accumulated Amortization		Weighted Average Original Life (years)		Gross Carrying Amount		Accumulated Amortization
	15.67	$	13,840	$	11,911		15.67	$	13,840	$	11,647

Aggregate amortization expense for patents and licenses was $264,000, $345,000 and $269,000 for 2016, 2015 and 2014, respectively. Estimated future amortization expense for each of the years set forth below ending December 31 is as follows (in thousands):

2017	$151
2018	$119
2019	$119
2020	$119
2021	$119