CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows provided by (used in) operating activities:
Net loss	$ (5,540)	$ (19,636)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	1,446	854
Stock-based compensation	2,094	3,184
Other	255	60
Changes in operating assets and liabilities:
Accounts and other receivables	1,596	(3,916)
Prepaid expenses and other current assets	5,306	1,539
Long-term deposits	(4,889)	(6,783)
Other assets	748	(4,841)
Accounts payable	(338)	3,762
Accrued compensation	(1,041)	(2,003)
Other current liabilities	(1,288)	1,742
Deferred revenue	(2,456)	(2,108)
Other long-term liabilities	(661)	4,231
Net cash used in operating activities	(4,768)	(23,915)
Cash flows provided by (used in) investing activities:
Purchases of short-term investments	0	(8,930)
Proceeds from maturities of short-term investments	3,000	14,000
Purchases of property and equipment	(30)	(9)
Net cash provided by investing activities	2,970	5,061
Cash flows provided by (used in) financing activities:
Cash paid for purchases of treasury shares	(30,642)	0
Proceeds from issuance of common stock under employee stock purchase plan	63	109
Proceeds from stock options exercises	0	371
Net cash provided by (used in) financing activities	(30,579)	480
Net decrease in cash and cash equivalents	(32,377)	(18,374)
Cash and cash equivalents:
Beginning of period	86,478	110,988
End of period	54,101	92,614
Supplemental disclosure of cash flow information:
Cash paid for income taxes	20	25
Supplemental disclosure of non-cash operating, investing, and financing activities:
Release of restricted stock units and awards under company stock plan	2,554	7,065
Leased assets obtained in exchange for new operating lease liabilities	$ 577	$ 0