Intangible Assets (Tables)

3 Months Ended

Mar. 31, 2020

Goodwill And Intangible Assets Disclosure [Abstract]

Reconciliation of Intangible Assets

The reconciliation of intangible assets for the three months ended March 31, 2020 and 2019 was as follows (in thousands):

	March 31,			March 31,
	2020			2019
Patented technologies
Gross carrying cost at beginning of period	$	68,322		$	68,322
Gross carrying cost at end of period		68,322			68,322
Accumulated amortization at beginning of period		(40,653	)		(38,193	)
Amortization expense		(615	)		(615	)
Accumulated amortization at end of period		(41,268	)		(38,808	)
Net book value at end of period	$	27,054		$	29,514