Basic and Diluted Net Loss Per Common Share - Summary of Computation of Basic and Diluted Net Loss Available to Stockholders (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Basic net loss per share:
Basic net loss per share	$ (1.95)	$ (0.54)
Diluted net loss per share:
Diluted net loss per share	$ (1.95)	$ (0.54)
Class A common stock
Basic net loss per share:
Allocation of undistributed losses	$ (8,279)	$ (2,272)
Number of shares used in per share computation (as converted)	4,242	4,242
Basic net loss per share	$ (1.95)	$ (0.54)
Diluted net loss per share:
Allocation of undistributed losses	$ (8,279)	$ (2,272)
Number of shares used in per share computation (as converted)	4,242	4,242
Diluted net loss per share	$ (1.95)	$ (0.54)
Common stock equivalents excluded from calculation of diluted net loss per share as the effect would have been anti-dilutive:	379	445
Class B common stock
Basic net loss per share:
Allocation of undistributed losses	$ (4,568)	$ (1,253)
Number of shares used in per share computation (as converted)	2,340	2,340
Basic net loss per share	$ (1.95)	$ (0.54)
Diluted net loss per share:
Allocation of undistributed losses	$ (4,568)	$ (1,253)
Number of shares used in per share computation (as converted)	2,340	2,340
Diluted net loss per share	$ (1.95)	$ (0.54)
Series C convertible preferred stock
Basic net loss per share:
Allocation of undistributed losses	$ (1,483)	$ (407)
Number of shares used in per share computation (as converted)	760	760
Basic net loss per share	$ (1.95)	$ (0.54)
Diluted net loss per share:
Allocation of undistributed losses	$ (1,483)	$ (407)
Number of shares used in per share computation (as converted)	760	760
Diluted net loss per share	$ (1.95)	$ (0.54)