UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF REDEEMABLE NONCONTROLLING INTEREST AND STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Class A Common Stock	Class B Common Stock	Total Stockholders’ Equity Attributable to Semrush Holdings, Inc.	Common Stock Class A Common Stock	Common Stock Class B Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Noncontrolling Interest
Beginning balance (in shares) at Dec. 31, 2022					43,743,174	97,843,570
Beginning balance at Dec. 31, 2022	$ 199,904				$ 0	$ 1	$ 274,057	$ (1,206)	$ (72,948)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of Class B Common Stock to Class A Common Stock (in shares)					74,239,844	74,239,844
Conversion of Class B Common Stock to Class A Common Stock	0				$ 1	$ (1)
Issuance of common stock upon exercise of stock options (in shares)					88,957
Issuance of common stock upon exercise of stock options	67						67
Issuance of common stock in connection with employee stock purchase plan (in shares)					38,879
Issuance of common stock in connection with employee stock purchase plan	264						264
Issuance of common stock upon vesting of restricted stock units (in shares)					71,557
Stock-based compensation expense	2,796						2,796
Cumulative translation adjustment	365							365
Unrealized gain (loss) on investments	(83)							(83)
Net income (loss)	(9,860)								(9,860)
Ending balance (in shares) at Mar. 31, 2023					118,182,411	23,603,726
Ending balance at Mar. 31, 2023	193,453				$ 1	$ 0	277,184	(924)	(82,808)
Beginning balance (in shares) at Dec. 31, 2022					43,743,174	97,843,570
Beginning balance at Dec. 31, 2022	199,904				$ 0	$ 1	274,057	(1,206)	(72,948)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative translation adjustment	193
Unrealized gain (loss) on investments	(1,179)
Net income (loss)	(5,924)
Ending balance (in shares) at Sep. 30, 2023					119,610,733	23,482,057
Ending balance at Sep. 30, 2023	204,769				$ 1	$ 0	285,831	(2,191)	(78,872)
Beginning balance (in shares) at Mar. 31, 2023					118,182,411	23,603,726
Beginning balance at Mar. 31, 2023	193,453				$ 1	$ 0	277,184	(924)	(82,808)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)					583,137
Issuance of common stock upon exercise of stock options	235						235
Issuance of common stock upon vesting of restricted stock units (in shares)					264,920
Stock-based compensation expense	3,765						3,765
Cumulative translation adjustment	(120)							(120)
Unrealized gain (loss) on investments	(1,160)							(1,160)
Net income (loss)	(279)								(279)
Ending balance (in shares) at Jun. 30, 2023					119,030,468	23,603,726
Ending balance at Jun. 30, 2023	195,894				$ 1	$ 0	281,184	(2,204)	(83,087)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of Class B Common Stock to Class A Common Stock (in shares)					175,000	175,000
Issuance of common stock upon exercise of stock options (in shares)					325,870
Issuance of common stock upon exercise of stock options	444						444
Issuance of common stock upon vesting of restricted stock units (in shares)					79,395	53,331
Stock-based compensation expense	4,203						4,203
Cumulative translation adjustment	(51)							(51)
Unrealized gain (loss) on investments	64							64
Net income (loss)	4,215								4,215
Ending balance (in shares) at Sep. 30, 2023					119,610,733	23,482,057
Ending balance at Sep. 30, 2023	204,769				$ 1	$ 0	285,831	(2,191)	(78,872)
Redeemable Noncontrolling Interest, Ending balance at Mar. 31, 2024	0
Beginning balance (in shares) at Dec. 31, 2023		120,629,000	23,482,000		120,629,147	23,482,057
Beginning balance at Dec. 31, 2023	224,315			$ 219,149	$ 1	$ 0	291,898	(752)	(71,998)	$ 5,166
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)					469,879
Issuance of common stock upon exercise of stock options	844			844			844
Issuance of common stock upon vesting of restricted stock units (in shares)					145,844
Stock-based compensation expense	5,115			5,115			5,115
Cumulative translation adjustment	(485)			(485)				(485)
Unrealized gain (loss) on investments	(744)			(744)				(744)
Net income (loss)	2,138			2,138					2,138
Net loss attributable to noncontrolling interest	(135)									(135)
Ending balance (in shares) at Mar. 31, 2024					121,244,870	23,482,057
Ending balance at Mar. 31, 2024	231,048			226,017	$ 1	$ 0	297,857	(1,981)	(69,860)	5,031
Redeemable Noncontrolling Interest, Ending balance at Sep. 30, 2024	0
Beginning balance (in shares) at Dec. 31, 2023		120,629,000	23,482,000		120,629,147	23,482,057
Beginning balance at Dec. 31, 2023	$ 224,315			219,149	$ 1	$ 0	291,898	(752)	(71,998)	5,166
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of Class B Common Stock to Class A Common Stock (in shares)					409,801
Issuance of common stock upon exercise of stock options (in shares)	1,464,641
Cumulative translation adjustment	$ 754
Unrealized gain (loss) on investments	1,698
Net income (loss)	4,891
Ending balance (in shares) at Sep. 30, 2024		123,500,000	23,072,000		123,500,426	23,072,256
Ending balance at Sep. 30, 2024	258,995			248,518	$ 1	$ 0	313,924	1,700	(67,107)	10,477
Redeemable Noncontrolling Interest, Beginning balance at Mar. 31, 2024	0
Increase (Decrease) in Temporary Equity [Roll Forward]
Acquisition of redeemable noncontrolling interest (See Note 9)	9,846
Net loss attributable to redeemable noncontrolling interest	(70)
Reclassification for Tender Offer obligations (See Note 9)	(2,021)
Recording of redeemable noncontrolling interest at redemption value (See Note 9)	978
Redeemable Noncontrolling Interest, Ending balance at Jun. 30, 2024	8,733
Beginning balance (in shares) at Mar. 31, 2024					121,244,870	23,482,057
Beginning balance at Mar. 31, 2024	231,048			226,017	$ 1	$ 0	297,857	(1,981)	(69,860)	5,031
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of Class B Common Stock to Class A Common Stock (in shares)					409,801	409,801
Issuance of common stock upon exercise of stock options (in shares)					720,880
Issuance of common stock upon exercise of stock options	2,209			2,209			2,209
Issuance of common stock upon vesting of restricted stock units (in shares)					685,891
Stock-based compensation expense	7,015			7,015			7,015
Cumulative translation adjustment	(119)			(119)				(119)
Unrealized gain (loss) on investments	(184)			(184)				(184)
Net income (loss)	1,659			1,659					1,659
Net loss attributable to noncontrolling interest	(228)									(228)
Recording of redeemable noncontrolling interest at redemption value (See Note 9)	(978)			(978)			(978)
Ending balance (in shares) at Jun. 30, 2024					123,061,442	23,072,256
Ending balance at Jun. 30, 2024	240,422			235,619	$ 1	$ 0	306,103	(2,284)	(68,201)	4,803
Increase (Decrease) in Temporary Equity [Roll Forward]
Reclassification for Tender Offer obligations (See Note 9)	(1,615)
Reclassification of redeemable noncontrolling interest to noncontrolling interest	7,118									7,118
Redeemable Noncontrolling Interest, Ending balance at Sep. 30, 2024	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of Class B Common Stock to Class A Common Stock (in shares)					409,801
Issuance of common stock upon exercise of stock options (in shares)					273,882
Issuance of common stock upon exercise of stock options	647			647			647
Issuance of common stock upon vesting of restricted stock units (in shares)					165,102
Stock-based compensation expense	7,174			7,174			7,174
Cumulative translation adjustment	1,358			1,358				1,358
Unrealized gain (loss) on investments	2,626			2,626				2,626
Net income (loss)	1,094			1,094					1,094
Net loss attributable to noncontrolling interest	(376)									(376)
Reclassification of redeemable noncontrolling interest to noncontrolling interest	7,118									7,118
Acquisition of additional noncontrolling shares	(1,068)									(1,068)
Ending balance (in shares) at Sep. 30, 2024		123,500,000	23,072,000		123,500,426	23,072,256
Ending balance at Sep. 30, 2024	$ 258,995			$ 248,518	$ 1	$ 0	$ 313,924	$ 1,700	$ (67,107)	$ 10,477