Stockholder's Equity - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options to Purchase Common Stock Exercised	(124,455)	(30,607)
Montrose 2017 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options to Purchase Common Stock Outstanding Beginning Balance	2,579,566	2,036,729	2,036,729
Options to Purchase Common Stock Granted	233,955	547,884
Options to Purchase Common Stock Forfeited/cancelled	(34,619)	(23,082)
Options to Purchase Common Stock Exercised	(101,279)	(11,547)
Options to Purchase Common Stock Outstanding Ending Balance	2,677,623	2,549,984	2,579,566	2,036,729
Options to Purchase Common Stock Exercisable	1,305,511
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted-Average Exercise Price per Share Outstanding Beginning Balance	$ 31	$ 26	$ 26
Weighted-Average Exercise Price per Share Granted	32	44
Weighted-Average Exercise Price per Share Forfeited/cancelled	35	36
Weighted-Average Exercise Price per Share Exercised	25	27
Weighted-Average Exercise Price per Share Outstanding Ending Balance	31	30	31	$ 26
Weighted-Average Exercise Price per Share Exercisable	29
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted Average Grant Date Fair Value per Share Outstanding Beginning Balance	15	14	14
Weighted Average Grant Date Fair Value per Share Granted	14	16
Weighted Average Grant Date Fair Value per Share Ending Balance	$ 15	$ 14	$ 15	$ 14
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted Average Remaining Contract Life (in Years) Outstanding	7 years 9 months 10 days	8 years 5 months 15 days	7 years 9 months 3 days	8 years 3 months 18 days
Weighted Average Remaining Contract Life (in Years) Exercisable	7 years 2 months 8 days
Aggregate Intrinsic Value of In-The-Money Options Outstanding	$ 21,127	$ 59,955	$ 37,292	$ 91,030
Aggregate Intrinsic Value of In-The-Money Options Exercised	2,467	$ 313
Aggregate Intrinsic Value of In-The-Money Options Exercisable	$ 11,880
Montrose Amended and Restated 2013 Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options to Purchase Common Stock Outstanding Beginning Balance	855,695	897,674	897,674
Options to Purchase Common Stock Exercised	(23,176)	(19,060)
Options to Purchase Common Stock Outstanding Ending Balance	832,519	878,614	855,695	897,674
Options to Purchase Common Stock Exercisable	832,519
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted-Average Exercise Price per Share Outstanding Beginning Balance	$ 6	$ 6	$ 6
Weighted-Average Exercise Price per Share Exercised	9	6
Weighted-Average Exercise Price per Share Outstanding Ending Balance	6	6	6	$ 6
Weighted-Average Exercise Price per Share Exercisable	6
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted Average Grant Date Fair Value per Share Outstanding Beginning Balance	2	2	2
Weighted Average Grant Date Fair Value per Share Ending Balance	$ 2	$ 2	$ 2	$ 2
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted Average Remaining Contract Life (in Years) Outstanding	3 years 10 days	4 years 1 month 17 days	3 years 3 months 21 days	4 years 4 months 13 days
Weighted Average Remaining Contract Life (in Years) Exercisable	3 years 10 days
Aggregate Intrinsic Value of In-The-Money Options Outstanding	$ 24,393	$ 40,860	$ 32,478	$ 57,529
Aggregate Intrinsic Value of In-The-Money Options Exercised	963	$ 821
Aggregate Intrinsic Value of In-The-Money Options Exercisable	$ 24,393