Condensed Statements of Changes in Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total		Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive (Loss) Income
Balance at Dec. 31, 2020	$ (37,417)				$ 4	$ 1,149	$ (38,570)
Temporary equity, balance, Shares at Dec. 31, 2020			3,731,208	12,542,198
Temporary equity, balance at Dec. 31, 2020			$ 20,147	$ 74,550
Balance, Shares at Dec. 31, 2020					3,530,975
Stock-based compensation expense	165					165
Net loss	(6,800)						(6,800)
Balance at Mar. 31, 2021	(44,052)				$ 4	1,314	(45,370)
Balance at Mar. 31, 2021			3,731,208	12,542,198
Balance at Mar. 31, 2021			$ 20,147	$ 74,550
Balance, Shares at Mar. 31, 2021					3,530,975
Balance at Dec. 31, 2021	130,504	[1]			$ 27	220,530	(89,964)	$ (89)
Balance, Shares at Dec. 31, 2021					26,475,812
Exercise of stock options	106					106
Exercise of stock options, shares					24,262
Issuance of common stock from employee stock purchase plan	293					293
Issuance of common stock from employee stock purchase plan, shares					26,804
Stock-based compensation expense	1,242					1,242
Unrealized loss on short-term investments	(300)							(300)
Net loss	(17,394)						(17,394)
Balance at Mar. 31, 2022	$ 114,451				$ 27	$ 222,171	$ (107,358)	$ (389)
Balance at Mar. 31, 2022	0
Balance, Shares at Mar. 31, 2022					26,526,878

[1] The balance sheet at December 31, 2021 has been derived from the audited financial statements included in Rain Therapeutics Inc.’s Annual Report on Form 10-K filed on March 3, 2022.