Principal Business Activity and Significant Accounting Policies - Disaggregation of revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of revenue
Total net sales									$ 709,431	$ 528,614	$ 266,687
Product
Disaggregation of revenue
Total net sales	$ 134,894	$ 161,534	$ 194,606	$ 126,084	$ 95,141	$ 108,524	$ 148,713	$ 97,851	617,118	450,229	266,687
Services
Disaggregation of revenue
Total net sales	$ 19,442	$ 24,491	$ 26,028	$ 22,352	$ 15,883	$ 22,858	$ 22,429	$ 17,215	92,313	78,385
Domestic
Disaggregation of revenue
Total net sales									703,299	522,749	261,526
Domestic | Product
Disaggregation of revenue
Total net sales									610,986	444,364	261,526
Domestic | Services
Disaggregation of revenue
Total net sales									92,313	78,385
Foreign
Disaggregation of revenue
Total net sales									6,132	5,865	5,161
Foreign | Product
Disaggregation of revenue
Total net sales									$ 6,132	$ 5,865	$ 5,161
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Disaggregation of revenue
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year								1 year