Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]
Balance at Dec. 31, 2019	$ 49,450	$ 50	$ 12	$ 188,103	$ (138,715)
Balance, shares at Dec. 31, 2019		10,000	12,446,000
Issuance of common stock, net of issuance costs	38,603	$ 0	$ 3	38,600	0
Issuance of common stock, net of issuance costs, shares		0	2,704,000
Exercise of stock options	135	$ 0	$ 0	135	0
Exercise of stock options, shares		0	8,000
Issuance of restricted common stock	0	$ 0	$ 0	0	0
Issuance of restricted common stock, shares		0	242,000
Forfeiture of restricted common stock	0	$ 0	$ 0	0	0
Forfeiture of restricted common stock, shares		0	(7,000)
Purchase and retirement of common stock	(1,568)	$ 0	$ 0	(1,568)	0
Purchase and retirement of common stock, shares		0	(77,000)
Stock-based compensation	7,274	$ 0	$ 0	7,274	0
Net loss	(24,721)	0	0	0	(24,721)
Balance at Sep. 30, 2020	69,173	$ 50	$ 15	232,544	(163,436)
Balance, shares at Sep. 30, 2020		10,000	15,316,000
Balance at Jun. 30, 2020	37,277	$ 50	$ 13	192,298	(155,084)
Balance, shares at Jun. 30, 2020		10,000	12,659,000
Issuance of common stock, net of issuance costs	38,029	$ 0	$ 2	38,027	0
Issuance of common stock, net of issuance costs, shares		0	2,676,000
Issuance of restricted common stock	0	$ 0	$ 0	0	0
Issuance of restricted common stock, shares		0	13,000
Forfeiture of restricted common stock	0	$ 0	$ 0	0	0
Forfeiture of restricted common stock, shares		0	(3,000)
Purchase and retirement of common stock	(448)	$ 0	$ 0	(448)	0
Purchase and retirement of common stock, shares		0	(29,000)
Stock-based compensation	2,667	$ 0	$ 0	2,667	0
Net loss	(8,352)	0	0	0	(8,352)
Balance at Sep. 30, 2020	69,173	$ 50	$ 15	232,544	(163,436)
Balance, shares at Sep. 30, 2020		10,000	15,316,000
Balance at Dec. 31, 2020	83,839	$ 50	$ 17	255,024	(171,252)
Balance, shares at Dec. 31, 2020		10,000	16,735,000
Issuance of common stock, net of issuance costs, shares			0
Exercise of stock options	$ 4,030	$ 0	$ 0	4,030	0
Exercise of stock options, shares	170,000	0	170,000
Issuance of restricted common stock	$ 0	$ 0	$ 0	0	0
Issuance of restricted common stock, shares		0	223,000
Vesting of restricted stock units	0	$ 0	$ 0	0	0
Vesting of restricted stock units,shares		0	112,000
Forfeiture of restricted common stock	0	$ 0	$ 0	0	0
Forfeiture of restricted common stock, shares		0	(51,000)
Purchase and retirement of common stock	(8,928)	$ 0	$ 0	(8,928)	0
Purchase and retirement of common stock, shares		0	(256,000)
Stock-based compensation	10,459	$ 0	$ 0	10,459	0
Net loss	(26,515)	0	0	0	(26,515)
Balance at Sep. 30, 2021	62,885	$ 50	$ 17	260,585	(197,767)
Balance, shares at Sep. 30, 2021		10,000	16,933,000
Balance at Jun. 30, 2021	65,242	$ 50	$ 17	260,071	(194,896)
Balance, shares at Jun. 30, 2021		10,000	16,943,000
Exercise of stock options	$ 2,955	$ 0	$ 0	2,955	0
Exercise of stock options, shares	100,000	0	100,000
Issuance of restricted common stock	$ 0	$ 0	$ 0	0	0
Issuance of restricted common stock, shares		0	25,000
Forfeiture of restricted common stock	0	$ 0	$ 0	0	0
Forfeiture of restricted common stock, shares		0	(16,000)
Purchase and retirement of common stock	(4,079)	$ 0	$ 0	(4,079)	0
Purchase and retirement of common stock, shares		0	(119,000)
Stock-based compensation	1,638	$ 0	$ 0	1,638	0
Net loss	(2,871)	0	0	0	(2,871)
Balance at Sep. 30, 2021	$ 62,885	$ 50	$ 17	$ 260,585	$ (197,767)
Balance, shares at Sep. 30, 2021		10,000	16,933,000