Intangible Assets (Tables)

9 Months Ended

Sep. 30, 2020

Goodwill And Intangible Assets Disclosure [Abstract]

Reconciliation of Intangible Assets

The reconciliation of intangible assets for the nine months ended September 30, 2020 and 2019 was as follows (in thousands):

	September 30,			September 30,
	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		(1,845	)		(1,845	)
Accumulated amortization at end of period		(42,498	)		(40,038	)
Net book value at end of period	$	25,824		$	28,284