Consolidated Statements of Stockholders Equity (Deficit) - USD ($) $ in Thousands		Common Stock Class A		Common Stock Class B		Additional Paid-In Capital	Accumulated Deficit	Class A	Class B	Total
Impact of accounting standard update							$ 340			$ 340
Beginning balance at Dec. 31, 2018		$ 1	[1]	$ 1	[1]	$ 590,538	(471,238)			119,302
Beginning balance (in shares) at Dec. 31, 2018	[1]	5,240,073		7,714,036
Conversion from Class B to Class A common stock	[1]	$ 0		$ 0
Conversion from Class B to Class A common stock (in shares)	[1]	1,104,091		(1,104,091)
Issuance of common stock upon exercise of stock options and vesting of restricted stock		$ 0	[1]	$ 0	[1]	103				103
Issuance of common stock upon exercise of stock options and vesting of restricted stock (in shares)	[1]	23,911		27,444
Share-based compensation						2,974				2,974
Net income (loss)							(5,275)	$ (2,313)	$ (2,962)	(5,275)
Ending balance at Mar. 31, 2019		$ 1	[1]	$ 1	[1]	593,615	(476,173)			117,444
Ending balance (in shares) at Mar. 31, 2019	[1]	6,368,075		6,637,389
Beginning balance at Dec. 31, 2019		$ 1	[1]	$ 1	[1]	599,976	(531,979)			67,999
Beginning balance (in shares) at Dec. 31, 2019	[1]	7,799,093		5,464,196
Conversion from Class B to Class A common stock	[1]	$ 0		$ 0
Conversion from Class B to Class A common stock (in shares)	[1]	1,835,947		(1,835,947)
Issuance of common stock upon exercise of stock options and vesting of restricted stock		$ 0	[1]	$ 0	[1]	486				486
Issuance of common stock upon exercise of stock options and vesting of restricted stock (in shares)	[1]	92,243		25,999
Share-based compensation						2,321				2,321
Net income (loss)							(20,145)	$ (13,363)	$ (6,782)	(20,145)
Ending balance at Mar. 31, 2020		$ 1	[1]	$ 1	[1]	$ 602,783	$ (552,124)			$ 50,661
Ending balance (in shares) at Mar. 31, 2020	[1]	9,727,283		3,654,248

[1] Reflects the 1-for-15 reverse stock split that became effective on June 14, 2019.