Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended			6 Months Ended		12 Months Ended
	Oct. 10, 2017	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2018	Dec. 31, 2017
Significant Accounting Policies [Line Items]
Entity Incorporation Date Of Incorporation					Jan. 11, 1991
Concentration risk, customer					no customers each accounted for 10% or more of the Company’s revenues	two customers each accounted for 10% or more of the Company’s revenues
Options and warrants excluded from the calculation of diluted shares		785,697		0	785,697	0
Production and importation permission description					22 million pounds in 2015 and was reduced by approximately 4.5 million pounds each year to end at zero in 2020.
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent								35.00%
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount			$ 1,400
Payables to Customers		$ 11,300	$ 9,800		$ 11,300			$ 9,800
Business Combination, Consideration Transferred, Total	$ 209,000
Revenue from Contract with Customer, Including Assessed Tax		57,831		$ 52,231	100,259	$ 91,061
Operating Loss Carryforwards		5,400			$ 5,400
Operating Loss Carryforwards, Limitations on Use					2.8 million of which are subject to annual limitations of approximately $1.3 million.
Operating Loss Carry Forwards Expirations Date					2021
State and Local Jurisdiction [Member]
Significant Accounting Policies [Line Items]
Operating Loss Carryforwards		3,600			$ 3,600
PNC Bank [Member]
Significant Accounting Policies [Line Items]
Proceeds from Lines of Credit	80,000				105,000
Line of Credit Facility, Maximum Borrowing Capacity	150,000	80,000			80,000
Debt Instrument, Face Amount		$ 55,000			55,000
Term Loan [Member]
Significant Accounting Policies [Line Items]
Debt Instrument, Face Amount	$ 105,000
Scenario, Plan [Member]
Significant Accounting Policies [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent							21.00%
Accounting Standards Update 2016-09 [Member]
Significant Accounting Policies [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income								$ 2,400
Financial Service [Member]
Significant Accounting Policies [Line Items]
Revenue from Contract with Customer, Including Assessed Tax					$ 1,200	$ 1,200
Sales Revenue, Net [Member]
Significant Accounting Policies [Line Items]
Aggregate percentage of revenue the from customers accounted for more than 10%						41.00%
Customer
Significant Accounting Policies [Line Items]
Accounts receivable, net				$ 6,500		$ 6,500