Redeemable convertible preferred stock (Details) - USD ($) $ in Thousands	Aug. 06, 2018	Jun. 30, 2018	Sep. 30, 2017
Temporary Equity [Line Items]
Authorized Shares (in shares)		32,675,074	32,675,074
Issued Shares (in shares)		32,482,590	32,482,590
Outstanding Shares (in shares)		32,482,590	32,482,590
Carrying Value		$ 90,341	$ 90,341
Liquidation Preference		$ 90,976	$ 90,976
Series A Preferred Stock
Temporary Equity [Line Items]
Authorized Shares (in shares)		10,035,000	10,035,000
Issued Shares (in shares)		10,005,000	10,005,000
Outstanding Shares (in shares)		10,005,000	10,005,000
Carrying Value		$ 15,060	$ 15,060
Liquidation Preference		$ 15,008	$ 15,008
Series B Preferred Stock
Temporary Equity [Line Items]
Authorized Shares (in shares)		3,881,250	3,881,250
Issued Shares (in shares)		3,730,000	3,730,000
Outstanding Shares (in shares)		3,730,000	3,730,000
Carrying Value		$ 5,926	$ 5,926
Liquidation Preference		$ 5,968	$ 5,968
Series C Preferred Stock
Temporary Equity [Line Items]
Authorized Shares (in shares)		11,700,000	11,700,000
Issued Shares (in shares)		11,688,766	11,688,766
Outstanding Shares (in shares)		11,688,766	11,688,766
Carrying Value		$ 26,556	$ 26,556
Liquidation Preference		$ 25,000	$ 25,000
Series D Preferred Stock
Temporary Equity [Line Items]
Authorized Shares (in shares)		7,058,824	7,058,824
Issued Shares (in shares)		7,058,824	7,058,824
Outstanding Shares (in shares)		7,058,824	7,058,824
Carrying Value		$ 42,799	$ 42,799
Liquidation Preference		$ 45,000	$ 45,000
Subsequent Event
Temporary Equity [Line Items]
Number of shares of common stock issued for each share of redeemable convertible preferred stock (shares)	1
Common shares issued in conversion of outstanding shares of redeemable convertible preferred stock (shares)	32,482,590

The number of new shares issued in the conversion of stock in a noncash (or part noncash) transaction. Noncash is defined as transactions during a period that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

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Number of shares issued for each share of convertible preferred stock that is converted.

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Carrying amount, attributable to parent, of an entity's issued and outstanding stock which is not included within permanent equity. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. Includes stock with a put option held by an ESOP and stock redeemable by a holder only in the event of a change in control of the issuer.

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The aggregate liquidation preference (or restrictions) of stock classified as temporary equity that has a preference in involuntary liquidation considerably in excess of the par or stated value of the shares. The liquidation preference is the difference between the preference in liquidation and the par or stated values of the share. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with put option held by ESOP and stock redeemable by holder only in the event of a change in control of the issuer.

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The number of securities classified as temporary equity that have been sold (or granted) to the entity's shareholders. Securities issued include securities outstanding and securities held in treasury. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with put option held by ESOP and stock redeemable by holder only in the event of a change in control of the issuer.

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