Consolidated Statements of Stockholders Equity (Deficit) - USD ($) $ in Thousands	Common Stock Class A	Common Stock Class B	Additional Paid-In Capital	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment [Member]	Accumulated Deficit	Class A	Class B	Cumulative Effect, Period of Adoption, Adjustment [Member]	Total
Beginning balance at Dec. 31, 2018	$ 1	$ 1	$ 590,538	$ 340	$ (471,238)			$ 340	$ 119,302
Beginning balance (in shares) at Dec. 31, 2018	5,240,073	7,714,036
Conversion from Class B to Class A common stock	$ 0	$ 0
Conversion from Class B to Class A common stock (in shares)	1,104,091	(1,104,091)
Issuance of common stock upon exercise of stock options and vesting of restricted stock, net of tax withholdings	$ 0	$ 0	103						103
Issuance of common stock upon exercise of stock options and vesting of restricted stock (in shares)	23,911	27,444
Share-based compensation			2,974						2,974
Net income (loss)					(5,275)				(5,275)
Ending balance at Mar. 31, 2019	$ 1	$ 1	593,615		(476,173)				117,444
Ending balance (in shares) at Mar. 31, 2019	6,368,075	6,637,389
Beginning balance at Dec. 31, 2018	$ 1	$ 1	590,538	340	(471,238)			340	119,302
Beginning balance (in shares) at Dec. 31, 2018	5,240,073	7,714,036
Net income (loss)						$ (6,159)	$ (6,864)		(13,023)
Ending balance at Jun. 30, 2019	$ 1	$ 1	595,330		(483,921)				111,411
Ending balance (in shares) at Jun. 30, 2019	6,659,066	6,426,829
Beginning balance at Dec. 31, 2018	$ 1	$ 1	590,538	$ 340	(471,238)			$ 340	119,302
Beginning balance (in shares) at Dec. 31, 2018	5,240,073	7,714,036
Net income (loss)									(61,100)
Ending balance at Dec. 31, 2019	$ 1	$ 1	599,976		(531,979)				67,999
Ending balance (in shares) at Dec. 31, 2019	7,799,093	5,464,196
Beginning balance at Mar. 31, 2019	$ 1	$ 1	593,615		(476,173)				117,444
Beginning balance (in shares) at Mar. 31, 2019	6,368,075	6,637,389
Conversion from Class B to Class A common stock	$ 0	$ 0
Conversion from Class B to Class A common stock (in shares)	210,664	(210,664)
Issuance of common stock upon exercise of stock options and vesting of restricted stock, net of tax withholdings	$ 0	$ 0	(9)						(9)
Issuance of common stock upon exercise of stock options and vesting of restricted stock (in shares)	80,391	139
Share-based compensation			1,724						1,724
Other	$ 0	$ 0
Other (in shares)	(64)	(35)
Net income (loss)					(7,748)	(3,927)	(3,821)		(7,748)
Ending balance at Jun. 30, 2019	$ 1	$ 1	595,330		(483,921)				111,411
Ending balance (in shares) at Jun. 30, 2019	6,659,066	6,426,829
Beginning balance at Dec. 31, 2019	$ 1	$ 1	599,976		(531,979)				67,999
Beginning balance (in shares) at Dec. 31, 2019	7,799,093	5,464,196
Conversion from Class B to Class A common stock	$ 0	$ 0
Conversion from Class B to Class A common stock (in shares)	1,835,947	(1,835,947)
Issuance of common stock upon exercise of stock options and vesting of restricted stock, net of tax withholdings	$ 0	$ 0	486						486
Issuance of common stock upon exercise of stock options and vesting of restricted stock (in shares)	92,243	25,999
Share-based compensation			2,321						2,321
Net income (loss)					(20,145)				(20,145)
Ending balance at Mar. 31, 2020	$ 1	$ 1	602,783		(552,124)				50,661
Ending balance (in shares) at Mar. 31, 2020	9,727,283	3,654,248
Beginning balance at Dec. 31, 2019	$ 1	$ 1	599,976		(531,979)				67,999
Beginning balance (in shares) at Dec. 31, 2019	7,799,093	5,464,196
Net income (loss)						(13,242)	(5,789)		(19,031)
Ending balance at Jun. 30, 2020	$ 1	$ 1	604,877		(551,010)				53,869
Ending balance (in shares) at Jun. 30, 2020	9,886,644	3,654,147
Beginning balance at Mar. 31, 2020	$ 1	$ 1	602,783		(552,124)				50,661
Beginning balance (in shares) at Mar. 31, 2020	9,727,283	3,654,248
Conversion from Class B to Class A common stock	$ 0	$ 0
Conversion from Class B to Class A common stock (in shares)	101	(101)
Issuance of common stock upon exercise of stock options and vesting of restricted stock, net of tax withholdings	$ 0		(3)						(3)
Issuance of common stock upon exercise of stock options and vesting of restricted stock (in shares)	159,260
Share-based compensation			2,097						2,097
Net income (loss)					1,114	$ 811	$ 303		1,114
Ending balance at Jun. 30, 2020	$ 1	$ 1	$ 604,877		$ (551,010)				$ 53,869
Ending balance (in shares) at Jun. 30, 2020	9,886,644	3,654,147