UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Income Statement [Abstract]
Revenue	$ 90,951,000	$ 74,693,000	$ 176,763,000	$ 145,563,000
Cost of revenue	14,957,000	12,972,000	29,602,000	25,611,000
Gross profit	75,994,000	61,721,000	147,161,000	119,952,000
Operating expenses
Sales and marketing	35,000,000	30,237,000	68,921,000	65,733,000
Research and development	19,288,000	14,116,000	36,592,000	27,996,000
General and administrative	18,312,000	19,388,000	36,786,000	38,028,000
Exit costs	0	309,000	0	1,292,000
Total operating expenses	72,600,000	64,050,000	142,299,000	133,049,000
Income (loss) from operations	3,394,000	(2,329,000)	4,862,000	(13,097,000)
Other income, net	2,616,000	2,919,000	6,255,000	4,624,000
Income (loss) before income taxes	6,010,000	590,000	11,117,000	(8,473,000)
Provision for income taxes	4,649,000	869,000	7,753,000	1,666,000
Net income (loss)	1,361,000	(279,000)	3,364,000	(10,139,000)
Net loss attributable to noncontrolling interest in consolidated subsidiaries	(298,000)	0	(433,000)	0
Net income (loss) attributable to Semrush Holdings, Inc.	$ 1,659,000	$ (279,000)	$ 3,797,000	$ (10,139,000)
Net income (loss) per share attributable to common stockholders
Net income (loss) attributable to Semrush Holdings, Inc. per share attributable to common stockholders—basic (in dollars per share)	$ 0.01	$ 0.00	$ 0.03	$ (0.07)
Net income (loss) attributable to Semrush Holdings, Inc. per share attributable to common stockholders—diluted (in dollars per share)	$ 0.01	$ 0.00	$ 0.03	$ (0.07)
Weighted-average number of shares of common stock used in computing net income (loss) per share attributable to common stockholders
Weighted-average number of shares of common stock used in computing net income (loss) per share attributable to common stockholders—basic (in shares)	145,678,323	142,239,140	145,121,951	141,946,425
Weighted-average number of shares of common stock used in computing net income (loss) per share attributable to common stockholders—diluted (in shares)	148,825,311	142,239,140	148,261,407	141,946,425
Comprehensive income (loss)
Net income (loss)	$ 1,361,000	$ (279,000)	$ 3,364,000	$ (10,139,000)
Other comprehensive income (loss)
Foreign currency translation adjustments	(119,000)	(120,000)	(604,000)	245,000
Unrealized loss on investments	(184,000)	(1,160,000)	(928,000)	(1,243,000)
Comprehensive income (loss)	1,058,000	(1,559,000)	1,832,000	(11,137,000)
Comprehensive loss attributable to noncontrolling interest in consolidated subsidiaries	(298,000)	0	(433,000)	0
Comprehensive income (loss) attributable to Semrush Holdings, Inc.	$ 1,356,000	$ (1,559,000)	$ 2,265,000	$ (11,137,000)