Carrying value as of the balance sheet date of the portion of long-term debt due within one year or the operating cycle if longer identified as Convertible Notes Payable. Convertible Notes Payable is a written promise to pay a note which can be exchanged for a specified amount of another, related security, at the option of the issuer and the holder.

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The price per share of the conversion feature embedded in the debt instrument.

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

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Redeemable Convertible Notes - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Feb. 20, 2018	Dec. 31, 2017	Aug. 19, 2015
Debt Instrument [Line Items]
Derivative liability	$ 0
Redeemable convertible notes, outstanding balance			$ 0	$ 5,085,000
Convertible Notes
Debt Instrument [Line Items]
Convertible notes, total outstanding principal amount					$ 37,000,000
Convertible notes, maturity date	Feb. 19, 2018
Convertible notes, maturity period	30 months
Redeemable convertible notes, conversion feature	$ 1,500,000
Redeemable convertible notes, estimated fair value	37,100,000
Redeemable convertible notes, debt discount	1,400,000
Derivative liability	0
Redeemable convertible notes, interest expense	$ 0	$ 0
Convertible Notes \| After Reverse Stock Split
Debt Instrument [Line Items]
Redeemable convertible notes, conversion per share price	$ 137.85