Consolidated Statements of Changes in Stockholders’ Equity - USD ($) $ in Thousands	Total	Revision of Prior Period, Accounting Standards Update, Adjustment	Series A Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Additional Paid-in Capital Revision of Prior Period, Accounting Standards Update, Adjustment	Accumulated Deficit	Accumulated Deficit Revision of Prior Period, Accounting Standards Update, Adjustment	Accumulated Other Comprehensive Income/(Loss)
Beginning balance (in shares) at Dec. 31, 2019				93,001,597
Beginning balance at Dec. 31, 2019	$ 331,446			$ 93	$ 583,097		$ (251,786)		$ 42
Increase (Decrease) in Stockholders' Equity
Issuance of common stock pursuant to exercise of stock options (in shares)				738,398
Issuance of common stock pursuant to exercise of stock options	3,916			$ 1	3,915
Issuance of common stock pursuant to settlement of restricted stock units (in shares)				320,440
Issuance of common stock pursuant to settlement of restricted stock units	0
Common stock surrendered for employees' tax liability upon settlement of restricted stock units (in shares)				(102,661)
Common stock surrendered for employees' tax liability upon settlement of restricted stock units	(3,307)				(3,307)
Stock-based compensation	7,715				7,715
Other comprehensive income	533								533
Net loss	(60,117)						(60,117)
Ending balance (in shares) at Mar. 31, 2020				93,957,774
Ending balance at Mar. 31, 2020	280,186			$ 94	591,420		(311,903)		575
Beginning balance (in shares) at Dec. 31, 2019				93,001,597
Beginning balance at Dec. 31, 2019	$ 331,446			$ 93	583,097		(251,786)		42
Ending balance (in shares) at Dec. 31, 2020	40,000		40,000
Ending balance at Dec. 31, 2020	$ 39,823		$ 39,823
Ending balance (in shares) at Dec. 31, 2020	103,000,594			103,000,594
Ending balance at Dec. 31, 2020	$ 590,557	$ (162,478)		$ 103	860,556	$ (170,240)	(270,313)	$ 7,762	211
Increase (Decrease) in Stockholders' Equity
Accounting Standards Update [Extensible List]	rdfn:AccountingStandardsUpdate202006Member
Issuance of convertible preferred stock, net			$ 11
Common Stock Dividends, Shares				30,640
Issuance of common stock pursuant to exercise of stock options (in shares)	670,050			670,050
Issuance of common stock pursuant to exercise of stock options	$ 3,463			$ 1	3,462
Issuance of common stock pursuant to settlement of restricted stock units (in shares)				360,351
Issuance of common stock pursuant to settlement of restricted stock units	0
Common stock surrendered for employees' tax liability upon settlement of restricted stock units (in shares)				(115,030)
Common stock surrendered for employees' tax liability upon settlement of restricted stock units	(10,860)				(10,860)
Purchases of capped calls related to convertible senior notes	(54,480)				(54,480)
Issuance of common stock in connection with conversion of convertible senior notes (in shares)				36,980
Issuance of common stock in connection with conversion of convertible senior notes	(52)				(52)
Stock-based compensation	13,316				13,316
Other comprehensive income	(50)								(50)
Net loss	$ (35,784)						(35,784)
Ending balance (in shares) at Mar. 31, 2021	40,000		40,000
Ending balance at Mar. 31, 2021	$ 39,834		$ 39,834
Ending balance (in shares) at Mar. 31, 2021	103,983,585			103,983,585
Ending balance at Mar. 31, 2021	$ 343,632			$ 104	$ 641,702		$ (298,335)		$ 161