Stockholders' Equity And Stock-Based Compensation (Narrative) (Details) - USD ($)						1 Months Ended				3 Months Ended
	Jan. 01, 2022	Jun. 30, 2021	Feb. 25, 2021	Feb. 05, 2021	Feb. 04, 2021	Jul. 31, 2021	Mar. 31, 2021	Feb. 28, 2021	Feb. 04, 2021	Mar. 31, 2022	Mar. 31, 2021	Apr. 14, 2022	Dec. 31, 2021	May 31, 2021	Jun. 30, 2020	Nov. 30, 2017	Dec. 31, 2016	Dec. 31, 2014
Stockholders' Equity [Line Items]
Preferred stock, shares authorized										50,000,000			50,000,000
Preferred stock, par value										$ 0.001			$ 0.001
Preferred stock, shares outstanding										0			0
Common stock, shares authorized										500,000,000			500,000,000
Common stock, par value										$ 0.001			$ 0.001
Proceeds from issuance of common stock											$ 4,892,000
Common stock, shares issued										29,802,000			29,716,000
Total stock-based compensation expense										$ 2,007,000	6,965,000
2017 Employee Stock Purchase Plan [Member]
Stockholders' Equity [Line Items]
Common stock, shares issued										85,844
Shares authorized										250,000
Increase in shares available for issuance threshold of common stock outstanding, number of shares										450,000
Increase in shares available for issuance threshold of common stock outstanding, percent outstanding										1.50%
Shares available for grant										563,252
2017 Inducement Equity Incentive Plan [Member]
Stockholders' Equity [Line Items]
Term period										10 years
Shares authorized														1,000,000		1,000,000
Shares available for grant										775,066
2017 Plan [Member]
Stockholders' Equity [Line Items]
Term period										10 years
Shares authorized										1,500,000
Additional common stock reserved for issuance	1,188,657
Increase in shares available for issuance threshold of common stock outstanding, number of shares										1,200,000
Increase in shares available for issuance threshold of common stock outstanding, percent outstanding										4.00%
Shares available for grant										2,339,229
Rights Offering [Member]
Stockholders' Equity [Line Items]
Price per share															$ 7.01
Warrants/rights outstanding										0
Net proceeds									$ 4,500,000
Period the warrants are exercisable after issuance										30 days
Percentage requirement for warrant redemption										200.00%
Warrants exercised				5,139					636,432
Redemption per warrant			$ 0.01	$ 0.01
Period of time required for redemption of warrants										10 days
First Vesting Portion [Member] | 2017 Inducement Equity Incentive Plan [Member]
Stockholders' Equity [Line Items]
Vesting percentage										25.00%
General And Administrative [Member]
Stockholders' Equity [Line Items]
Total stock-based compensation expense										$ 1,006,000	2,038,000
Research And Development [Member]
Stockholders' Equity [Line Items]
Total stock-based compensation expense										457,000	3,166,000
Stock Options [Member]
Stockholders' Equity [Line Items]
Total stock-based compensation expense								$ 0			4,200,000
Time-Based Options [Member]
Stockholders' Equity [Line Items]
Total stock-based compensation expense										1,807,000	1,770,000
Performance Shares [Member]
Stockholders' Equity [Line Items]
Total stock-based compensation expense										$ 84,000	$ 5,141,000
Subsequent Event [Member]
Stockholders' Equity [Line Items]
Common stock, par value												$ 0.001
Private Placement [Member]
Stockholders' Equity [Line Items]
Common stock, par value																		$ 0.001
Proceeds from issuance of common stock		$ 8,400,000
Chairman, Robert W. Duggan [Member] | Private Placement [Member]
Stockholders' Equity [Line Items]
Shares sold		3,048,780
Common stock, par value		$ 0.001
Price per share		$ 16.40
Aggregate issuance costs		$ 41,000,000.0
Proceeds from issuance of common stock						$ 8,400,000
Net proceeds		$ 50,000,000.0
Common stock, shares issued		3,048,780
Directors [Member] | Private Placement [Member]
Stockholders' Equity [Line Items]
Proceeds from issuance of common stock						$ 8,400,000
Common Stock [Member]
Stockholders' Equity [Line Items]
Shares issued											158,000
Warrants exercised											40,000
Common Stock [Member] | Rights Offering [Member]
Stockholders' Equity [Line Items]
Warrants/rights outstanding															641,571
Robert W. Duggan [Member] | Private Placement [Member]
Stockholders' Equity [Line Items]
Price per share		$ 16.40
MDB Capital Group, LLC [Member] | Initial Public Offering [Member]
Stockholders' Equity [Line Items]
Price per share																	$ 5.00
Warrants/rights outstanding										0
Number of common shares called by issuance of warrants																	574,985
Common stock received from rights/warrants exercised							68,958				68,958
Warrants exercised							85,385
Exercisable period of warrants or rights										5 years
MDB Capital Group, LLC [Member] | Private Placement [Member]
Stockholders' Equity [Line Items]
Price per share																		$ 2.67
Number of common shares called by issuance of warrants																		299,625
Common stock received from rights/warrants exercised							40,563				40,563
Warrants exercised							45,638
Exercisable period of warrants or rights										7 years
Stifel, Nicolaus & Company Inc. [Member] | At the Market Offering [Member]
Stockholders' Equity [Line Items]
Value of warrants/rights					$ 60,000,000.0				$ 60,000,000.0
Warrants/rights outstanding					288,490				288,490
Exercise price of warrants/rights					$ 27.73				$ 27.73
Net proceeds					$ 7,400,000