Long-term Debt - Additional Information (Detail)	1 Months Ended	9 Months Ended
	Jan. 31, 2018 USD ($)	Sep. 30, 2018 USD ($) installment	Dec. 31, 2017 USD ($)	Mar. 31, 2017 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)	Oct. 31, 2015 USD ($)	Oct. 31, 2014 USD ($)	Apr. 30, 2014 USD ($)
Line of Credit Facility [Line Items]
Term loans payable		$ 50,446,000	$ 49,315,000
Term Loan Agreement
Line of Credit Facility [Line Items]
Credit facility, maximum borrowing capacity							$ 60,000,000.0		$ 45,000,000.0
Credit facility, additional borrowing capacity					$ 5,000,000.0	$ 10,000,000.0		$ 10,000,000.0
Unused borrowing capacity, amount				$ 15,000,000
Percentage of accrue interest		12.00%					12.50%
Percentage of deferred payment		3.00%
Interest deferral period		6 years
Deferred interest payment		$ 5,400,000
Term loans payable		$ 50,400,000		$ 49,300,000
Interest payment period		7 years
Number of installments | installment		4
Percentage payment up on repayment of principal amount		2.00%
Long term liability		$ 1,100,000
Minimum liquidity		2,000,000.0
Annual revenue requirements		100,000,000
Increase in annual revenue in fiscal years		15,000,000.0
Term Loan Agreement | Maximum
Line of Credit Facility [Line Items]
Credit facility, additional borrowing capacity									$ 20,000,000.0
Revolving Credit Facility | Secured Revolving Loan Facility
Line of Credit Facility [Line Items]
Credit facility, maximum borrowing capacity		$ 15,000,000
Variable rate	4.75%
Percentage of accrue interest	8.75%
Long-term Line of Credit	$ 0
Prime Rate | Revolving Credit Facility | Secured Revolving Loan Facility
Line of Credit Facility [Line Items]
Variable rate	0.50%