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v3.23.2

Stockholder's Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions | 3 Months Ended | 6 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Jun. 30, 2023 | Jun. 30, 2022 | Jun. 30, 2023 | Jun. 30, 2022 | Dec. 31, 2021 | Dec. 31, 2022
Class Of Stock [Line Items] |  |  |  |  |  |  |
Common stock, shares authorized |  | 190,000,000 |  | 190,000,000 |  |  | 190,000,000
Common stock, par value |  | $ 0.000004 |  | $ 0.000004 |  |  | $ 0.000004
Total unrecognized stock-based compensation expense related to unvested options, restricted stock and stock appreciation rights granted under the Plans |  | $ 141.5 | $ 162.1 | $ 141.5 | $ 162.1 |  |
Unrecognized expense expected to be recognized period |  |  |  | 3 years |  |  |
Shares, granted | [1] |  |  | 90,116 | 25,289 |  |
Restricted shares outstanding |  | 2,701,920 | 2,064,197 | 2,701,920 | 2,064,197 |  |
Montrose 2017 Stock Incentive Plan |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |
Shares, granted |  | 53,164 |  | 253,587 | 0 |  |
Montrose 2017 Stock Incentive Plan | Restricted Stock |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |
Shares RSAs granted |  | 0 | 0 | 17,346 | 10,920 |  |
Montrose 2017 Stock Incentive Plan | Stock Options | Board of Directors |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |
Shares of vested over period |  |  |  | 4 years |  |  |
Montrose 2017 Stock Incentive Plan | Stock Options | Executive Officers |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |
Shares of vested over period |  |  |  | 3 years |  |  |
Vesting frequency of period |  |  |  | 1 year |  |  |
Montrose 2017 Stock Incentive Plan | Stock Options | On the two-year anniversary of the grant | Board of Directors |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |
Shares, vesting rights, percentage |  |  |  | 50.00% |  |  |
Montrose 2017 Stock Incentive Plan | Stock Options | Fourth Anniversary | Board of Directors |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |
Shares, vesting rights, percentage |  |  |  | 50.00% |  |  |
Montrose Amended and Restated 2013 Stock Option Plan |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |
Shares outstanding from exercised options |  | 1,478,423 | 1,243,272 | 1,478,423 | 1,243,272 |  |
Two Thousand Seventeen Plan | Stock Appreciation Rights (SARs) |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |
Shares, granted |  |  |  | 3,000,000 |  |  |
Exercise price |  |  |  |  |  | $ 66.79 |
Shares of vested over period |  |  |  |  |  | 5 years |
Remaining contractual terms |  |  |  | 10 years |  |  |
Fair value vested in period |  |  |  | $ 46.0 |  |  |
Weighted average remaining contract life |  |  |  | 8 years 5 months 15 days |  |  |
Supplemental Incentive Plans |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |
Shares, granted |  | 123,932 | 0 | 253,587 | 95,404 |  |
Supplemental Incentive Plans | RSUs |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |
Shares of vested over period |  |  |  | 4 years |  |  |
Supplemental Incentive Plans | RSUs | First Quater |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |
Shares, vesting rights, percentage |  |  |  | 33.33% |  |  |
Supplemental Incentive Plans | RSUs | First Anniversary |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |
Shares, vesting rights, percentage |  |  |  | 33.33% |  |  |
Supplemental Incentive Plans | RSUs | Second Anniversary |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |
Shares, vesting rights, percentage |  |  |  | 33.33% |  |  |
[1] | Represents the non-cash release of common shares due to the vesting of restricted stock.

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