Quarterly Financial Results (Unaudited) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Interim Period, Costs Not Allocable [Line Items]
Sales									$ 158,733,000	$ 157,893,000
Operating expenses	$ 28,412,000	$ 16,318,000	$ 16,430,000	$ 19,385,000	$ 19,195,000	$ 18,317,000	$ 18,381,000	$ 18,953,000
Loss from operations	(11,350,000)	(503,000)	(3,436,000)	(7,648,000)	(3,325,000)	(4,858,000)	(6,679,000)	(6,234,000)	(22,937,000)	(21,096,000)
Net loss from continuing operations	(11,637,000)	(537,000)	(3,552,000)	(6,214,000)	(2,910,000)	(3,308,000)	(3,294,000)	(6,497,000)	(21,940,000)	(16,009,000)
Net income (loss) from discontinued operations					(573,000)	(1,036,000)	50,630,000	243,000	0	49,264,000
Net (loss) income	$ (11,637,000)	$ (537,000)	$ (3,552,000)	$ (6,214,000)	$ (3,483,000)	$ (4,344,000)	$ 47,336,000	$ (6,254,000)	(21,940,000)	33,255,000
Net loss continuing operations per share
Basic (in dollars per share)	$ (0.65)	$ (0.03)	$ (0.20)	$ (0.35)	$ (0.17)	$ (0.19)	$ (0.19)	$ (0.38)
Diluted (in dollars per share)	(0.65)	(0.03)	(0.20)	(0.35)	(0.17)	(0.19)	(0.19)	(0.38)
Net income (loss) discontinued operations per share
Basic (in dollars per share)					(0.03)	(0.06)	2.90	0.01
Diluted (in dollars per share)					(0.03)	(0.06)	2.90	0.01
Net (loss) income per share
Basic (in dollars per share)	(0.65)	(0.03)	(0.20)	(0.35)	(0.20)	(0.25)	2.71	(0.36)
Diluted (in dollars per share)	$ (0.65)	$ (0.03)	$ (0.20)	$ (0.35)	$ (0.20)	$ (0.25)	$ 2.71	$ (0.36)
Goodwill and intangible impairment charges	$ 10,490,000								$ 10,490,000	$ 0
Product
Interim Period, Costs Not Allocable [Line Items]
Sales	20,926,000	$ 16,650,000	$ 13,949,000	$ 13,094,000	$ 18,713,000	$ 14,808,000	$ 15,189,000	$ 13,215,000
Cost of product and service sales	11,996,000	10,422,000	9,554,000	9,636,000	11,131,000	10,823,000	12,649,000	8,284,000
Service
Interim Period, Costs Not Allocable [Line Items]
Sales	23,201,000	24,462,000	22,977,000	23,474,000	23,763,000	24,503,000	24,541,000	23,161,000
Cost of product and service sales	$ 15,069,000	$ 14,875,000	$ 14,378,000	$ 15,195,000	$ 15,475,000	$ 15,029,000	$ 15,379,000	$ 15,373,000