Revenue - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Disaggregation of Revenue
Customer revenue transferred over-time			27.90%	29.90%
Total net sales	$ 118,365	$ 144,848	$ 381,835	$ 475,097
Contract with customer, assets	36,891		36,891		$ 37,032
Contract with customer, liability	3,606		3,606		$ 4,472
Contract assets transferred to receivables			23,907
Cash proceeds from liability contract			3,286
Revenue recognized from contract liability	$ 175	$ 194	3,708	1,460
Over time
Disaggregation of Revenue
Customer revenue transferred over-time	32.20%	35.60%
Total net sales	$ 38,116	$ 51,519	106,439	141,862
Over time | Performance Based
Disaggregation of Revenue
Total net sales	27,316	37,488	76,606	104,309
Over time | Delivery Based
Disaggregation of Revenue
Total net sales	$ 10,800	$ 14,031	$ 29,833	$ 37,553
Point in time
Disaggregation of Revenue
Customer revenue transferred over-time	67.80%	64.40%	72.10%	70.10%
Total net sales	$ 80,249	$ 93,329	$ 275,396	$ 333,235