Share-Based Compensation	3 Months Ended
Mar. 31, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-Based Compensation	4. SHARE-BASED COMPENSATION The Wave Life Sciences Ltd. 2014 Equity Incentive Plan, as amended (the “2014 Plan”), authorizes the board of directors or a committee of the board of directors to, among other things, grant non-qualified share options, restricted awards, which include restricted shares and restricted share units (“RSUs”), and performance awards to eligible employees and directors of the Company. Options generally vest over periods of one to four years, and any options that are forfeited or cancelled are available to be granted again. The contractual life of options is generally five or ten years from the grant date. RSUs can be time-based or performance-based. Time-based RSUs generally vest over a period of one to four years. The vesting of performance-based RSUs is contingent on the achievement of certain performance milestones. Any RSUs that are forfeited are available to be granted again. In March 2021, the Compensation Committee approved an amendment and restatement of the Company’s outstanding 2019 performance-based RSUs to add an additional milestone to the existing milestones and granted 2021 performance-based RSUs with the same terms to employees who did not receive the 2019 performance-based RSUs. This modification did not result in any incremental expense and the Company did not recognize any expense related to the performance-based RSUs during the three months ended March 31, 2021 and 2020, as the related milestones were not considered probable of achievement as of March 31, 2021 and 2020, respectively. During the three months ended March 31, 2021, the Company granted 921,141 options and 1,020,559 RSUs to employees, of the RSUs granted 851,159 were time-based RSUs and 169,400 were performance-based RSUs. As of March 31, 2021, 579,478 ordinary shares remained available for future grant under the 2014 Plan. Employee Share Purchase Plan The Wave Life Sciences Ltd. Employee Share Purchase Plan (“ESPP”) allows all full-time and certain part-time employees to purchase the Company’s ordinary shares at a discount to fair market value. Eligible employees may enroll in a six-month offering period beginning on or about January 15^th and July 15^th each year. Shares are purchased at a price equal to 85% of the lower of the fair market value of the Company’s ordinary shares on the first business day or the last business day of an offering period. During the three months ended March 31, 2021, 44,036 ordinary shares were issued under the ESPP. As of March 31, 2021, there were 930,725 ordinary shares available for issuance under the ESPP.

Share-Based Compensation

3 Months Ended

Mar. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

4. SHARE-BASED COMPENSATION

The Wave Life Sciences Ltd. 2014 Equity Incentive Plan, as amended (the “2014 Plan”), authorizes the board of directors or a committee of the board of directors to, among other things, grant non-qualified share options, restricted awards, which include restricted shares and restricted share units (“RSUs”), and performance awards to eligible employees and directors of the Company. Options generally vest over periods of one to four years, and any options that are forfeited or cancelled are available to be granted again. The contractual life of options is generally five or ten years from the grant date. RSUs can be time-based or performance-based. Time-based RSUs generally vest over a period of one to four years. The vesting of performance-based RSUs is contingent on the achievement of certain performance milestones. Any RSUs that are forfeited are available to be granted again. In March 2021, the Compensation Committee approved an amendment and restatement of the Company’s outstanding 2019 performance-based RSUs to add an additional milestone to the existing milestones and granted 2021 performance-based RSUs with the same terms to employees who did not receive the 2019 performance-based RSUs. This modification did not result in any incremental expense and the Company did not recognize any expense related to the performance-based RSUs during the three months ended March 31, 2021 and 2020, as the related milestones were not considered probable of achievement as of March 31, 2021 and 2020, respectively.

During the three months ended March 31, 2021, the Company granted 921,141 options and 1,020,559 RSUs to employees, of the RSUs granted 851,159 were time-based RSUs and 169,400 were performance-based RSUs.

As of March 31, 2021, 579,478 ordinary shares remained available for future grant under the 2014 Plan.

Employee Share Purchase Plan

The Wave Life Sciences Ltd. Employee Share Purchase Plan (“ESPP”) allows all full-time and certain part-time employees to purchase the Company’s ordinary shares at a discount to fair market value. Eligible employees may enroll in a six-month offering period beginning on or about January 15^th and July 15^th each year. Shares are purchased at a price equal to 85% of the lower of the fair market value of the Company’s ordinary shares on the first business day or the last business day of an offering period. During the three months ended March 31, 2021, 44,036 ordinary shares were issued under the ESPP. As of March 31, 2021, there were 930,725 ordinary shares available for issuance under the ESPP.