Additional loan advances upon occurrence of certain funding conditions.

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Debt instrument, percentage of final payment due at maturity to outstanding.

+ References

No definition available.

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Debt instrument, percentage of prepaid closing charge during first twelve month following initial closing.

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- Definition

Debt instrument, percentage of prepaid closing charge thereafter to prior to maturity date.

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No definition available.

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- Definition

Debt instrument repayment fee percentage.

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No definition available.

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- Definition

Equity securities, or instruments exercisable or convertible into equity securities.

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No definition available.

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- Definition

Number of additional optional term loan advances.

+ References

No definition available.

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

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- Definition

Face (par) amount of debt instrument at time of issuance.

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- Definition

Amount of the fee that accompanies borrowing money under the debt instrument.

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- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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- Definition

Description of the interest rate as being fixed or variable, and, if variable, identification of the index or rate on which the interest rate is based and the number of points or percentage added to that index or rate to set the rate, and other pertinent information, such as frequency of rate resets.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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- Definition

Description of the payment terms of the debt instrument (for example, whether periodic payments include principal and frequency of payments) and discussion about any contingencies associated with the payment.

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Amount of the required periodic payments applied to principal.

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End date of debt instrument redemption period, in CCYY-MM-DD format.

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Start date of debt instrument redemption period, in CCYY-MM-DD format.

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- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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No definition available.

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Amount of unamortized debt discount (premium) and debt issuance costs.

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- Definition

Amount of the cost of borrowed funds accounted for as interest expense.

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Amount of interest payable on debt, including, but not limited to, trade payables.

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The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

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Borrowings - Loan Agreement - Additional Information (Detail)		1 Months Ended	12 Months Ended
	Jul. 02, 2018 USD ($) Loan	Dec. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Interest expense			$ 956,000	$ 34,650,000
Loan Agreement [Member]
Debt Instrument [Line Items]
Scheduled principle repayments			0
Interest expense			1,000,000
Term Loan [Member] \| Loan Agreement [Member]
Debt Instrument [Line Items]
Number of additional optional term loan advances \| Loan	2
Term Loan [Member] \| Loan Agreement [Member] \| Hercules Capital, Inc [Member]
Debt Instrument [Line Items]
Aggregate principal amount of loan	$ 25,000,000	$ 15,000,000	15,000,000
Debt instrument, initial advance received	$ 15,000,000
Debt instrument, interest rate terms	The term loan bears interest at an annual rate equal to the greater of 9.25% and 9.25% plus the prime rate of interest minus 5.25%.
Interest rate (as a percent)	9.25%
Debt instrument, term	18 months
Outstanding principal balance repayment start date	Feb. 01, 2020
Outstanding principal balance repayment end date	Aug. 01, 2021
Debt instruement, payment terms	The Loan Agreement provides for interest-only payments for eighteen months and repayment of the aggregate outstanding principal balance of the term loan in monthly installments starting on February 1, 2020 and continuing through August 1, 2021
Payment of debt instrument fee amount	$ 300,000	300,000	300,000
Debt instrument, repayment fee percentage	5.55%
Debt instrument, percentage of prepaid closing charge during first twelve month following initial closing	3.00%
Debt instrument, percentage of prepaid closing charge thereafter to prior to maturity date	1.00%
Equity securities, or instruments exercisable or convertible into equity securities			1,000,000
Debt discount discount and issuance costs		400,000	400,000
Payments of fee	$ 300,000	$ 300,000	300,000
Debt instrument, percentage of final payment due at maturity to outstanding debt		5.55%
Final fee payment due at maturity to outstanding debt		$ 800,000	$ 800,000
Percentage of effective interest rate		12.50%	12.50%
Term Loan [Member] \| Loan Agreement [Member] \| Hercules Capital, Inc [Member] \| Prime Rate [Member]
Debt Instrument [Line Items]
Debt instrument, percentage deducted from interest rate and prime rate	5.25%
Term Loan [Member] \| Loan Agreement [Member] \| Hercules Capital, Inc [Member] \| Prior To December 31, 2018 [Member]
Debt Instrument [Line Items]
Debt instrument, initial advance amount	$ 5,000,000
Term Loan [Member] \| Loan Agreement [Member] \| Hercules Capital, Inc [Member] \| Prior To December 31, 2019 [Member]
Debt Instrument [Line Items]
Debt instrument, initial advance amount	$ 5,000,000