Long-Term Debt - Additional Information (Detail)	1 Months Ended		12 Months Ended
	Oct. 31, 2015 USD ($)	Apr. 30, 2014 USD ($)	Dec. 31, 2017 USD ($) installment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jun. 30, 2016 USD ($)	Oct. 31, 2014 USD ($)
Line of Credit Facility [Line Items]
Credit facility, maximum borrowing capacity			$ 15,000,000
Term loans payable			49,315,000	$ 47,844,000
Property and equipment, net			14,057,000	12,158,000
Accumulated depreciation			17,248,000	14,816,000
Leased Property
Line of Credit Facility [Line Items]
Property and equipment, net			700,000	700,000
Accumulated depreciation			700,000	500,000
Term Loan Agreement
Line of Credit Facility [Line Items]
Credit facility, maximum borrowing capacity	$ 60,000,000.0	$ 45,000,000.0
Credit facility, outstanding		20,000,000
End of term payment		1,000,000
Amount of make-whole premium payment		300,000
Total charge to interest expense		1,400,000
Loss on extinguishment of debt		$ 600,000
Credit facility additional borrowing							$ 10,000,000
Percentage of accrue interest	12.00%
Percentage of deferred payment	3.00%
Deferred interest payment			4,300,000
Credit facility, additional borrowing capacity					$ 10,000,000	$ 5,000,000
Debt Instrument, Unused Borrowing Capacity, Amount				15,000,000
Term loans payable			$ 49,300,000	47,800,000
Interest payment period	7 years
Number of installments | installment			4
Percentage of redemption fee	4.00%
Percentage payment up on repayment of principal amount	2.00%
Long term liability	$ 1,100,000
Minimum liquidity covenant			$ 2,000,000.0
Annual revenue requirements			85,000,000
Increase in annual revenue in fiscal years			15,000,000.0
Interest expense			$ 6,200,000	$ 5,700,000	$ 4,000,000
Term Loan Agreement | Maximum
Line of Credit Facility [Line Items]
Percentage of accrue interest	12.50%
Term Loan Agreement | Minimum
Line of Credit Facility [Line Items]
Percentage of accrue interest	12.00%
Percentage of redemption fee	1.00%