Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities
Net loss	$ (39,151)	$ (30,543)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization	974	1,829
Loss on impairment of long-lived assets	0	5,784
Stock-based compensation expense	2,257	1,966
Write-off of lease receivable/prepaid commission assets		1,383
Changes in assets and liabilities
Prepaid expenses and other assets	(2,167)	1,299
Accounts payable	157	1,422
Deferred revenue	1,804	6,315
Accrued and other liabilities	3,949	(1,624)
Net cash used in operating activities	(32,177)	(12,169)
Cash flows from financing activities
Proceeds from issuance of common stock in connection with employee benefit plans	120	80
Proceeds from issuance of common stock in connection with exercise of options	308	315
Proceeds from issuance of common stock in private placement, net of issuance costs of $78		4,922
Net cash provided by financing activities	31,061	7,583
Net change in cash, cash equivalents, and restricted cash	(1,116)	(4,586)
Cash, cash equivalents, and restricted cash at beginning of period	62,971	67,557
Cash, cash equivalents, and restricted cash at end of period	61,855	62,971
Supplemental disclosure of noncash items
Right-of-use asset acquired through operating lease		470
Direct Offering [Member]
Cash flows from financing activities
Proceeds from issuance of common stock in offering	20,866
At-the-market Offering [Member]
Cash flows from financing activities
Proceeds from issuance of common stock in offering	$ 9,767	$ 2,266