Capital Stock - Summary of Series Preferred Stock (Details) - USD ($) $ in Thousands	2 Months Ended	12 Months Ended
Feb. 13, 2017	Dec. 31, 2018	Dec. 31, 2017
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of preferred stock to common stock		$ 0	$ 76,981
Redeemable Convertible Preferred Stock [Member]
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)	18,584,390		18,584,390
Beginning balance	$ 76,976		$ 76,976
Accretion of redeemable convertible preferred stock to redemption value	$ 5		$ 5
Conversion of preferred stock to common stock (in shares)	(18,584,390)		(18,584,390)
Conversion of preferred stock to common stock	$ (76,981)		$ (76,981)
Ending balance (in shares)	0
Ending balance	$ 0
Series A Redeemable Convertible Preferred Stock [Member]
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)	7,149,176		7,149,176
Beginning balance	$ 23,124		$ 23,124
Accretion of redeemable convertible preferred stock to redemption value	$ 1
Conversion of preferred stock to common stock (in shares)	(7,149,176)
Conversion of preferred stock to common stock	$ (23,125)
Ending balance (in shares)	0
Ending balance	$ 0
Series B Redeemable Convertible Preferred Stock [Member]
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)	2,166,651		2,166,651
Beginning balance	$ 12,975		$ 12,975
Accretion of redeemable convertible preferred stock to redemption value	$ 1
Conversion of preferred stock to common stock (in shares)	(2,166,651)
Conversion of preferred stock to common stock	$ (12,976)
Ending balance (in shares)	0
Ending balance	$ 0
Series C Redeemable Convertible Preferred Stock [Member]
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)	9,268,563		9,268,563
Beginning balance	$ 40,877		$ 40,877
Accretion of redeemable convertible preferred stock to redemption value	$ 3
Conversion of preferred stock to common stock (in shares)	(9,268,563)
Conversion of preferred stock to common stock	$ (40,880)
Ending balance (in shares)	0
Ending balance	$ 0

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The difference between the carrying amount of a financial instrument subject to a registration payment arrangement recorded as temporary equity prior to adoption of FSP EITF 00-19-2 and the carrying amount reclassified to permanent equity upon the adoption of FSP EITF 00-19-2. Recorded as a cumulative effect adjustment to the beginning balance of retained earnings. Does not apply to registration payment arrangements that are no longer outstanding upon adoption of FSP EITF 00-19-2.

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Number of shares issued during the period as a result of the conversion of convertible securities.

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Value of accretion of temporary equity to its redemption value during the period.

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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 number of securities classified as temporary equity that have been issued and are held by the entity's shareholders. Securities outstanding equals securities issued minus 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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