| Cover | 12 Months Ended |
| Dec. 31, 2022 | |
| Document Information [Line Items] | |
| Document Type | PRE 14A |
| Amendment Flag | false |
| Entity Information [Line Items] | |
| Entity Registrant Name | MERUS N.V. |
| Entity Central Index Key | 0001651311 |
| Pay vs Performance Disclosure - USD ($) | 12 Months Ended | ||
| Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020 | |
| Pay vs Performance Disclosure [Table] | |||
| Pay vs Performance [Table Text Block] | PAY VERSUS PERFORMANCE Pay Versus Performance Table The following table sets forth information concerning the c ompensation of o (a) (b) (c) (d) (e) (f) (g) (h)(5) Year Summary ($) Compensation ($)(1)(2) Average Non-PEO NEOs Average Non-PEO NEOs Value of Initial Fixed $100 Net ($) Total ($)(3) Peer Group ($)(4) 2022 5,744,794 -2,256,931 1,997,552 -53,411 109.87 113.65 -131.2 2021 7,540,935 11,523,096 2,031,414 3,116,021 225.85 126.45 -66.8 2020 5,049,022 5,589,212 1,453,520 1,380,032 124.5 126.42 -85.5 (1) The PEO for all three fiscal years is Sven (Bill) Ante Lundberg. Non-PEO NEOs represent the following executives by year: 2022: Hui Liu, Peter Silverman, Andrew Joe 2021: Hui Liu, Peter Silverman 2020: Hui Liu, Peter Silverman (2) Compensation Actually Paid (CAP) has been calculated based on the requirements and methodology set forth in the applicable SEC rules. The CAP calculation includes the end-of-year value of awards granted within the applicable fiscal year, the change in fair value from prior year end of vested awards and the change in the fair value of unvested awards granted in prior years, regardless of if, when or at which intrinsic value they will actually vest. To calculate CAP the following amounts were deducted from and added to the total compensation number shown in the Summary Compensation Table. 2022 2021 2020 PEO Average Non-CEO PEO Average Non-CEO PEO Average Non-CEO Total Compensation from Summary Compensation Table $ 5,744,794 $ 1,997,552 $ 7,540,935 $ 2,031,414 $ 5,049,022 $ 1,453,520 Adjustments for Equity Awards Adjustment for grant date values in the Summary Compensation Table $ (4,791,732 ) $ (1,367,010 ) $ (6,550,400 ) $ (1,389,468 ) $ (4,062,203 ) $ (840,427 ) Year-end $ 2,381,092 $ 669,935 $ 7,516,254 $ 1,531,846 $ 4,598,303 $ 654,243 Year-over-year difference of year-end $ (4,187,745 ) $ (949,302 ) $ 2,568,931 $ 739,590 $ 14,919 $ 129,725 Difference in fair values between prior year-end $ (1,403,339 ) $ (404,586 ) $ 447,375 $ 202,639 $ (10,829 ) $ (17,029 ) Total Adjustments for Equity Awards $ (8,001,725 ) $ (2,050,963 ) $ 3,982,161 $ 1,084,607 $ 540,190 $ (73,488 ) Compensation Actually Paid (as calculated) $ (2,256,931 ) $ (53,411 ) $ 11,523,096 $ 3,116,021 $ 5,589,212 $ 1,380,032 (3) Reflects cumulative Total Shareholder Return (TSR). It shows the growth of a $100 investment on December 31, 2019. (4) Peer Group TSR reflects the cumulative TSR of the NASDAQ Biotechnology Index(TR) index reported in our Stock Performance Graph in our Annual Report on Form 10-K. (5) We have chosen not to include a Company-Selected Measure in the Pay Versus Performance Table because we did not use any financial performance measures in setting pay-for-performance compensation in the 2022 fiscal year. | ||
| Named Executive Officers, Footnote [Text Block] | (1) The PEO for all three fiscal years is Sven (Bill) Ante Lundberg. Non-PEO NEOs represent the following executives by year: 2022: Hui Liu, Peter Silverman, Andrew Joe 2021: Hui Liu, Peter Silverman 2020: Hui Liu, Peter Silverman | ||
| Peer Group Issuers, Footnote [Text Block] | Peer Group TSR reflects the cumulative TSR of the NASDAQ Biotechnology Index(TR) index reported in our Stock Performance Graph in our Annual Report on Form 10-K. | ||
| PEO Total Compensation Amount | $ 5,744,794 | $ 7,540,935 | $ 5,049,022 |
| PEO Actually Paid Compensation Amount | $ (2,256,931) | 11,523,096 | 5,589,212 |
| Adjustment To PEO Compensation, Footnote [Text Block] | 2022 2021 2020 PEO Average Non-CEO PEO Average Non-CEO PEO Average Non-CEO Total Compensation from Summary Compensation Table $ 5,744,794 $ 1,997,552 $ 7,540,935 $ 2,031,414 $ 5,049,022 $ 1,453,520 Adjustments for Equity Awards Adjustment for grant date values in the Summary Compensation Table $ (4,791,732 ) $ (1,367,010 ) $ (6,550,400 ) $ (1,389,468 ) $ (4,062,203 ) $ (840,427 ) Year-end $ 2,381,092 $ 669,935 $ 7,516,254 $ 1,531,846 $ 4,598,303 $ 654,243 Year-over-year difference of year-end $ (4,187,745 ) $ (949,302 ) $ 2,568,931 $ 739,590 $ 14,919 $ 129,725 Difference in fair values between prior year-end $ (1,403,339 ) $ (404,586 ) $ 447,375 $ 202,639 $ (10,829 ) $ (17,029 ) Total Adjustments for Equity Awards $ (8,001,725 ) $ (2,050,963 ) $ 3,982,161 $ 1,084,607 $ 540,190 $ (73,488 ) Compensation Actually Paid (as calculated) $ (2,256,931 ) $ (53,411 ) $ 11,523,096 $ 3,116,021 $ 5,589,212 $ 1,380,032 | ||
| Non-PEO NEO Average Total Compensation Amount | $ 1,997,552 | 2,031,414 | 1,453,520 |
| Non-PEO NEO Average Compensation Actually Paid Amount | $ (53,411) | 3,116,021 | 1,380,032 |
| Adjustment to Non-PEO NEO Compensation Footnote [Text Block] | 2022 2021 2020 PEO Average Non-CEO PEO Average Non-CEO PEO Average Non-CEO Total Compensation from Summary Compensation Table $ 5,744,794 $ 1,997,552 $ 7,540,935 $ 2,031,414 $ 5,049,022 $ 1,453,520 Adjustments for Equity Awards Adjustment for grant date values in the Summary Compensation Table $ (4,791,732 ) $ (1,367,010 ) $ (6,550,400 ) $ (1,389,468 ) $ (4,062,203 ) $ (840,427 ) Year-end $ 2,381,092 $ 669,935 $ 7,516,254 $ 1,531,846 $ 4,598,303 $ 654,243 Year-over-year difference of year-end $ (4,187,745 ) $ (949,302 ) $ 2,568,931 $ 739,590 $ 14,919 $ 129,725 Difference in fair values between prior year-end $ (1,403,339 ) $ (404,586 ) $ 447,375 $ 202,639 $ (10,829 ) $ (17,029 ) Total Adjustments for Equity Awards $ (8,001,725 ) $ (2,050,963 ) $ 3,982,161 $ 1,084,607 $ 540,190 $ (73,488 ) Compensation Actually Paid (as calculated) $ (2,256,931 ) $ (53,411 ) $ 11,523,096 $ 3,116,021 $ 5,589,212 $ 1,380,032 | ||
| Compensation Actually Paid vs. Total Shareholder Return [Text Block] | |||
| Compensation Actually Paid vs. Net Income [Text Block] | |||
| Total Shareholder Return Vs Peer Group [Text Block] | |||
| Total Shareholder Return Amount | $ 109.87 | 225.85 | 124.5 |
| Peer Group Total Shareholder Return Amount | 113.65 | 126.45 | 126.42 |
| Net Income (Loss) | $ (131,200) | (66,800) | (85,500) |
| PEO Name | Sven (Bill) Ante Lundberg | ||
| PEO [Member] | Adjustment For Grant Date Values [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | $ (4,791,732) | (6,550,400) | (4,062,203) |
| PEO [Member] | Year-End Fair Value Of Unvested Awards Granted In The Current Year [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 2,381,092 | 7,516,254 | 4,598,303 |
| PEO [Member] | Year-Over-Year Difference Of YearEnd Fair Values For Unvested Awards Granted In Prior Years [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | (4,187,745) | 2,568,931 | 14,919 |
| PEO [Member] | Difference In Fair Values Between Prior YearEnd Fair Values And Vest Date Fair Values For Awards Granted In Prior Years [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | (1,403,339) | 447,375 | (10,829) |
| PEO [Member] | Total Adjustments [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | (8,001,725) | 3,982,161 | 540,190 |
| Non-PEO NEO [Member] | Adjustment For Grant Date Values [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | (1,367,010) | (1,389,468) | (840,427) |
| Non-PEO NEO [Member] | Year-End Fair Value Of Unvested Awards Granted In The Current Year [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 669,935 | 1,531,846 | 654,243 |
| Non-PEO NEO [Member] | Year-Over-Year Difference Of YearEnd Fair Values For Unvested Awards Granted In Prior Years [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | (949,302) | 739,590 | 129,725 |
| Non-PEO NEO [Member] | Difference In Fair Values Between Prior YearEnd Fair Values And Vest Date Fair Values For Awards Granted In Prior Years [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | (404,586) | 202,639 | (17,029) |
| Non-PEO NEO [Member] | Total Adjustments [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | $ (2,050,963) | $ 1,084,607 | $ (73,488) |
