Principal Business Activity and Significant Accounting Policies - Adopted Accounting Standard Updates (“ASU”) - Disaggregation of revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of revenue
Total net sales	$ 171,142	$ 87,178	$ 286,208	$ 154,207
Product
Disaggregation of revenue
Total net sales	148,713	87,178	246,564	154,207
Services
Disaggregation of revenue
Total net sales	22,429		39,644
U.S.
Disaggregation of revenue
Total net sales	169,707	85,857	283,178	151,767
U.S. | Product
Disaggregation of revenue
Total net sales	147,278	85,857	243,534	151,767
U.S. | Services
Disaggregation of revenue
Total net sales	22,429		39,644
Foreign
Disaggregation of revenue
Total net sales	1,435	1,321	3,030	2,440
Foreign | Product
Disaggregation of revenue
Total net sales	$ 1,435	$ 1,321	$ 3,030	$ 2,440