Consolidated Statements of Stockholders' Equity/Deficit-Unaudited - USD ($) shares in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Gain (Loss)	Treasury Stock
Balance, shares at Dec. 31, 2021		150,082
Balance, value at Dec. 31, 2021	$ 113,595,000	$ 150,000	$ 1,608,749,000	$ (1,487,776,000)	$ (10,000)	$ (7,518,000)
Stock-based compensation	2,772,000	$ 0	2,772,000	0	0	0
Issuance of common stock under Equity Incentive Plans, shares		0
Issuance of common stock under Equity Incentive Plans, value	(864,000)	$ 0	0	0	0	864,000
Net loss	(23,476,000)	0	0	(23,476,000)	0	0
Unrealized gain on investments	(27,000)	$ 0	0	0	(27,000)	0
Balance, shares at Mar. 31, 2022		150,082
Balance, value at Mar. 31, 2022	92,698,000	$ 150,000	1,605,898,000	(1,511,252,000)	(37,000)	(2,061,000)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures		0
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	698,000	$ 0	698,000	0	0	0
Stock Issued During Period, Value, Treasury Stock Reissued	$ 0	$ 0	(6,321,000)	0	0	(6,321,000)
Stock Issued During Period, Shares, Treasury Stock Reissued		0
Balance, shares at Dec. 31, 2022	189,214	189,214
Balance, value at Dec. 31, 2022	$ 117,124,000	$ 189,000	1,709,144,000	(1,589,720,000)	(428,000)	(2,061,000)
Stock-based compensation	3,415,000	0	3,415,000	0	0	0
Repurchase of common stock	(824,000)	0	0	0	0	(824,000)
Net loss	(31,934,000)	0	0	(31,934,000)	0	0
Unrealized gain on investments	$ 265,000	$ 0	0	0	265,000	0
Balance, shares at Mar. 31, 2023	190,430	190,430
Balance, value at Mar. 31, 2023	$ 88,046,000	$ 190,000	1,712,558,000	(1,621,654,000)	(163,000)	(2,885,000)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures		1,216
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	0	$ 1,000	$ (1,000)	$ 0	$ 0	$ 0
Stock Issued During Period, Value, Treasury Stock Reissued	$ 0