Revenue - Narratives (Details) - USD ($) $ in Thousands	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	Dec. 31, 2018
Disaggregation of Revenue
Total net sales	$ 115,576	$ 118,365	$ 141,563	$ 121,907	$ 141,331	$ 144,848	$ 190,701	$ 139,548	$ 497,411	$ 616,428	$ 581,064
Contract with customer, assets	37,843				37,032				37,843	37,032
Contract assets transferred to receivables									27,126	24,487
Cash proceeds from liability contract									803	4,358
Revenue recognized from contract liability									3,784	1,462	$ 1,141
Deferred revenue (Note 4)	7,144				8,446				7,144	8,446
Contract liabilities	$ 1,324				$ 4,472				$ 1,324	$ 4,472
Over time
Disaggregation of Revenue
Customer revenue transferred (percentage)									29.40%	30.30%	28.10%
Total net sales									$ 146,020	$ 186,775	$ 163,253
Over time | Performance Based
Disaggregation of Revenue
Total net sales									101,160	136,014	121,919
Over time | Delivery Based
Disaggregation of Revenue
Total net sales									$ 44,860	$ 50,761	$ 41,334
Point in time
Disaggregation of Revenue
Customer revenue transferred (percentage)									70.60%	69.70%	71.90%
Total net sales									$ 351,391	$ 429,653	$ 417,811