Earnings per Share (Details) $ / shares in Units, $ in Thousands			3 Months Ended						9 Months Ended
	Jun. 14, 2019	Jun. 13, 2019	Sep. 30, 2020 USD ($) $ / shares shares	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Sep. 30, 2019 USD ($) $ / shares shares	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Sep. 30, 2020 USD ($) $ / shares shares	Sep. 30, 2019 USD ($) $ / shares shares	Dec. 31, 2019 shares
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Reverse stock split, ratio of shares surrendered to shares received	15	15
Numerator:
Net income (loss) | $			$ (15,262)	$ 1,114	$ (20,145)	$ (26,196)	$ (7,748)	$ (5,275)	$ (34,293)	$ (39,219)
Denominator:
Weighted-average shares used to compute net income (loss) per share attributable to common stockholders-basic			15,861,948			13,133,056			14,206,273	13,049,851
Weighted average diluted shares outstanding (in shares)			15,861,948			13,133,056			14,206,273	13,049,851
Net income (loss) per share attributable to common stockholders-basic | $ / shares			$ (0.96)			$ (1.99)			$ (2.41)	$ (3.01)
Net income (loss) per share attributable to common stockholders-diluted | $ / shares			$ (0.96)			$ (1.99)			$ (2.41)	$ (3.01)
Class A
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Common stock, outstanding (in shares)			14,031,986						14,031,986		7,799,093
Numerator:
Net income (loss) attributable to common stockholders | $			$ (11,746)			$ (14,621)			$ (24,810)	$ (19,682)
Denominator:
Weighted-average shares used to compute net income (loss) per share attributable to common stockholders-basic			12,208,041			7,329,996			10,278,021	6,549,067
Weighted average diluted shares outstanding (in shares)			12,208,041			7,329,996			10,278,021	6,549,067
Net income (loss) per share attributable to common stockholders-basic | $ / shares			$ (0.96)			$ (1.99)			$ (2.41)	$ (3.01)
Net income (loss) per share attributable to common stockholders-diluted | $ / shares			$ (0.96)			$ (1.99)			$ (2.41)	$ (3.01)
Class B
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Common stock, outstanding (in shares)			3,653,820						3,653,820		5,464,196
Numerator:
Net income (loss) attributable to common stockholders | $			$ (3,516)			$ (11,575)			$ (9,483)	$ (19,537)
Denominator:
Weighted-average shares used to compute net income (loss) per share attributable to common stockholders-basic			3,653,907			5,803,060			3,928,252	6,500,784
Weighted average diluted shares outstanding (in shares)			3,653,907			5,803,060			3,928,252	6,500,784
Net income (loss) per share attributable to common stockholders-basic | $ / shares			$ (0.96)			$ (1.99)			$ (2.41)	$ (3.01)
Net income (loss) per share attributable to common stockholders-diluted | $ / shares			$ (0.96)			$ (1.99)			$ (2.41)	$ (3.01)
Class C
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Common stock, outstanding (in shares)			0						0		0