Stockholders' Equity and Stock-Based Compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands |
1 Months Ended | 3 Months Ended | 6 Months Ended | 12 Months Ended | |||
|---|---|---|---|---|---|---|---|
Apr. 30, 2026 |
Mar. 31, 2026 |
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Dec. 31, 2025 |
Jul. 31, 2025 |
|
| Share Repurchase Program [Line Items] | |||||||
| Repurchase of common stock | $ 100,245 | ||||||
| 2026 Plan | |||||||
| Share Repurchase Program [Line Items] | |||||||
| Description of terms of share-based payment arrangement | the Company’s shareholders approved the Amended and Restated 2026 Equity Incentive Plan (the “2026 Plan”) which amended and restated the 2015 Equity Incentive Plan (the “2015 Plan”) to (i) increase the number of shares of common stock reserved for issuance thereunder by 2,000,000 shares, (ii) effect the name change of the 2026 Plan, (iii) change the provision regarding non-employee director compensation limits from a number of shares of common stock not to exceed 500,000 shares to total compensation of (a) no more than $1,250,000 in combined cash and equity awards during such director’s year of appointment and (b) no more than $750,000 in combined cash and equity awards in any other year of service, and (iv) remove and revise certain provisions that were otherwise required for awards to qualify as performance-based compensation under Section 162(m) of the Internal Revenue Code of 1986, as amended, prior to the repeal of the applicable limitations thereunder. The 2026 Plan is administered by the Board of Directors (the “Board”) and permits the granting of stock, stock options, stock appreciation rights, restricted stock, restricted stock units and dividend equivalent rights to employees, officers, directors and consultants of the Company. | ||||||
| Increase in number of shares of common stock reserved for issuance | 2,000,000 | ||||||
| Maximum number of a non-employee director may receive | 500,000 | ||||||
| Maximum combined cash and equity awards during first year of appointment | $ 1,250 | ||||||
| Maximum combined cash and equity awards per year | $ 750 | ||||||
| Shares available for grants | 16,930,277 | 16,930,277 | |||||
| 2023 ESPP | Lantheus Holdings, Inc | |||||||
| Share Repurchase Program [Line Items] | |||||||
| Shares available for grants | 500,000 | 500,000 | |||||
| Eligible employees contribution percentage | 15.00% | 15.00% | |||||
| Purchase price percentage | 85.00% | ||||||
| Share issued | 58,907 | ||||||
| Number of shares available for issuance | 340,393 | ||||||
| Two Thousand Twenty Five Share Purchase Program | |||||||
| Share Repurchase Program [Line Items] | |||||||
| Stock repurchase program, authorized amount | $ 400,000 | ||||||
| Repurchase of common stock (in shares) | 0 | 0 | 3,500,000 | ||||
| Shares Acquired, Average Cost Per Share | $ 56.72 | ||||||
| Common stock remain available for repurchase | $ 200,000 | $ 200,000 | |||||
| Repurchase of common stock | $ 200,000 | ||||||