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Long Term Debt - FFG Loan Agreement - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended
	Mar. 08, 2019	Mar. 31, 2019	Dec. 31, 2018
Schedule Of Long Term Debt [Line Items]
Debt instrument, outstanding value		$ 19,546	$ 10,000
Debt instrument, current portion		$ 5,298	$ 1,687
FFG Loan Agreement [Member]
Schedule Of Long Term Debt [Line Items]
Debt instrument, maturity start date		Mar. 31, 2019
Debt instrument, maturity end date		Mar. 31, 2021
Debt instrument, outstanding value		$ 9,546
Debt instrument, current portion		$ 2,914
Number of years accelerated payment	3 years	5 years
Repayment of outstanding loan principal		$ 2,914
Percentage of minimum cash balance	70.00%
FFG Loan Agreement [Member] | Minimum [Member]
Schedule Of Long Term Debt [Line Items]
Debt instrument, interest rate		0.75%
FFG Loan Agreement [Member] | Maximum [Member]
Schedule Of Long Term Debt [Line Items]
Debt instrument, interest rate		2.00%

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

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Latest date the outstanding debt instruments are required to be repaid, in CCYY-MM-DD format.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

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