Debt Obligations - Additional Information (Details) - USD ($)		1 Months Ended		3 Months Ended		9 Months Ended
	Oct. 31, 2017	Jun. 30, 2017	May 31, 2017	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2017	Oct. 31, 2016	Jul. 31, 2017	Jan. 31, 2017
Debt Instrument [Line Items]
Line of credit facility maximum borrowing capacity	$ 50,000,000			$ 50,000,000		$ 50,000,000
Line of credit facility, outstanding borrowings	50,000,000			50,000,000		50,000,000
Line of credit facility with extended maturity date	$ 30,000,000			$ 30,000,000		$ 30,000,000
Line of credit facility, extended maturity month and year						2020-08
Interest rate, percentage	1.50%			1.50%		1.50%
Credit facility covenants compliance						As of January 31, 2017 and October 31, 2017, the Company was in compliance with all of the covenants contained in its credit facility with SVB.
Amortization of credit facility fees and debt issuance costs and discounts to interest expense				$ 100,000	$ 0	$ 200,000	$ 200,000
Credit facility fee balance	$ 0			0		0			$ 0
Debt issuance cost and discounts balance	400,000			400,000		400,000			0
Accreted balloon payment balance	2,600,000			2,600,000		$ 2,600,000			$ 1,400,000
Common Stock | IPO
Debt Instrument [Line Items]
Shares price								$ 7.00
Note Purchase Agreement | Convertible Promissory Notes
Debt Instrument [Line Items]
Line of credit facility maximum borrowing capacity			$ 25,000,000
Interest rate, percentage		8.00%
Required days of written notice			30 days
Notes expiry date						Dec. 31, 2019
Maturity period		18 months
Conversion of amount outstanding start date		Dec. 01, 2019
Period preceding conversion		30 days
Notes issued and sold	0
Note Purchase Agreement | Convertible Promissory Notes | Common Stock | IPO
Debt Instrument [Line Items]
Shares price		$ 7.00
Minimum
Debt Instrument [Line Items]
Amount to be paid on or before the maturity date						$ 20,000,000
9% Line of credit facility due in February 2019
Debt Instrument [Line Items]
Amount outstanding	$ 15,000,000			$ 15,000,000		$ 15,000,000
Credit facility, bears interest rate	9.00%			9.00%		9.00%
Line of credit facility, maturity month and year						2019-02
11.25% Line of credit facility due in February 2019
Debt Instrument [Line Items]
Amount outstanding	$ 35,000,000			$ 35,000,000		$ 35,000,000
Credit facility, bears interest rate	11.25%			11.25%		11.25%
Line of credit facility, maturity month and year						2019-02
Revolving Line of Credit | SVB Credit Facility
Debt Instrument [Line Items]
Line of credit facility maximum borrowing capacity	$ 20,000,000			$ 20,000,000		$ 20,000,000
Line of credit facility, outstanding borrowings	$ 19,000,000			$ 19,000,000		$ 19,000,000
Line of credit facility expiration period						2018-05
Line of credit facility, weighted average interest rate	4.84%			4.84%		4.84%