| Pay vs Performance Disclosure | 12 Months Ended |
| Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) |
| Pay vs Performance Disclosure [Table] | | | |
| Pay vs Performance [Table Text Block] | Value of Initial Fixed $100 Investment Based On: Summary Compensation Table Total for CEO (1) Compensation Actually Paid to CEO (1)(2) Average Summary Compensation Table Total for Non-CEO Average Compensation Actually Paid to Non-CEO TSR (5) Peer Group TSR (5) Net Income (Loss) Revenue Growth (6) Year $ $ $ $ $ $ $ % 2022 20,212,141 739,598 6,838,043 3,457,925 73.82 113.65 (443.3) 49 % 2021 15,315,579 (30,500,547) 6,176,702 (4,953,682) 151.12 126.45 (704.5) 195 % 2020 8,536,036 112,741,937 3,401,688 22,645,622 325.41 126.42 (268.9) 277 % | | |
| Company Selected Measure Name | Revenue growth | | |
| Named Executive Officers, Footnote [Text Block] | Samantha (Ying) Du has been the CEO of the Company since 2014.The Non-CEO NEOs included the following executives by year: 2022: Billy Cho, Rafael Amado, Harald Reinhart, Alan Bart Sandler, and Josh Smiley; | | |
| Peer Group Issuers, Footnote [Text Block] | The TSR peer group consists of the NASDAQ Biotechnology Index. | | |
| PEO Total Compensation Amount | $ 20,212,141 | $ 15,315,579 | $ 8,536,036 |
| PEO Actually Paid Compensation Amount | $ 739,598 | (30,500,547) | 112,741,937 |
| Adjustment To PEO Compensation, Footnote [Text Block] | Deductions from, and additions to, total compensation in the Summary Compensation Table by year to calculate Compensation Actually Paid include: 2022 2021 2020 Samantha Average Samantha Average Samantha Average Total Compensation from Summary Compensation Table 20,212,141 6,838,043 15,315,579 6,176,702 8,536,036 3,401,688 Adjustments for Equity Awards Adjustment for grant date values in the Summary Compensation Table (18,545,040) (6,059,426) (13,672,864) (5,279,647) (7,160,000) (2,837,222) Year-end fair value of unvested awards granted in the current year 13,913,094 4,783,831 3,708,060 1,299,614 27,099,276 4,659,848 Year-over-year difference of year-end fair values for unvested awards granted in prior years (10,827,207) (1,408,060) (36,638,677) (7,338,300) 66,533,031 16,035,472 Fair values at vest date for awards granted and vested in current year — — — 259,613 — — Difference in fair values between prior year-end fair values and vest date fair values for awards granted in prior years (4,013,390) (696,463) 787,355 (71,664) 17,733,594 1,385,836 Total Adjustments for Equity Awards (19,472,543) (3,380,118) (45,816,126) (11,130,384) 104,205,901 19,243,934 Compensation Actually Paid (as calculated) 739,598 3,457,925 (30,500,547) (4,953,682) 112,741,937 22,645,622 | | |
| Non-PEO NEO Average Total Compensation Amount | $ 6,838,043 | 6,176,702 | 3,401,688 |
| Non-PEO NEO Average Compensation Actually Paid Amount | $ 3,457,925 | (4,953,682) | 22,645,622 |
| Adjustment to Non-PEO NEO Compensation Footnote [Text Block] | Deductions from, and additions to, total compensation in the Summary Compensation Table by year to calculate Compensation Actually Paid include: 2022 2021 2020 Samantha Average Samantha Average Samantha Average Total Compensation from Summary Compensation Table 20,212,141 6,838,043 15,315,579 6,176,702 8,536,036 3,401,688 Adjustments for Equity Awards Adjustment for grant date values in the Summary Compensation Table (18,545,040) (6,059,426) (13,672,864) (5,279,647) (7,160,000) (2,837,222) Year-end fair value of unvested awards granted in the current year 13,913,094 4,783,831 3,708,060 1,299,614 27,099,276 4,659,848 Year-over-year difference of year-end fair values for unvested awards granted in prior years (10,827,207) (1,408,060) (36,638,677) (7,338,300) 66,533,031 16,035,472 Fair values at vest date for awards granted and vested in current year — — — 259,613 — — Difference in fair values between prior year-end fair values and vest date fair values for awards granted in prior years (4,013,390) (696,463) 787,355 (71,664) 17,733,594 1,385,836 Total Adjustments for Equity Awards (19,472,543) (3,380,118) (45,816,126) (11,130,384) 104,205,901 19,243,934 Compensation Actually Paid (as calculated) 739,598 3,457,925 (30,500,547) (4,953,682) 112,741,937 22,645,622 | | |
| Compensation Actually Paid vs. Total Shareholder Return [Text Block] | CAP Versus Cumulative TSR for the Company and Cumulative TSR of the Peer Group | | |
| Compensation Actually Paid vs. Net Income [Text Block] | CAP Versus Net Income | | |
| Compensation Actually Paid vs. Company Selected Measure [Text Block] | CAP Versus Revenue Growth | | |
| Total Shareholder Return Vs Peer Group [Text Block] | CAP Versus Cumulative TSR for the Company and Cumulative TSR of the Peer Group | | |
| Tabular List [Table Text Block] | Revenue growth • Product revenues • Year-end cash and cash equivalents | | |
| Total Shareholder Return Amount | $ 73.82 | 151.12 | 325.41 |
| Peer Group Total Shareholder Return Amount | 113.65 | 126.45 | 126.42 |
| Net Income (Loss) | $ (443,300,000) | $ (704,500,000) | $ (268,900,000) |
| Company Selected Measure Amount | 0.49 | 1.95 | 2.77 |
| PEO Name | Samantha (Ying) Du | | |
| Additional 402(v) Disclosure [Text Block] | The valuation assumptions for stock option awards included in Compensation Actually Paid are as follows: • The expected life of each stock option, which is determined using the “simplified method” and which takes into account the average of the remaining vesting period and remaining term as of the vest or fiscal year end date. • The exercise price and the asset price, which are based on the closing price for our ADSs on Nasdaq on the vest and fiscal year end date, respectively. • The risk-free rate, which is based on the Treasury Constant Maturity rate closest to the remaining expected life as of the vest or fiscal year end date. • Our historical volatility, which is based on the daily price history for our ADSs traded on Nasdaq for each expected life prior to each vest or fiscal year end date. • The annual dividend yield, which for Zai Lab was zero as we did not pay dividends and do not expect to pay any in the foreseeable future . | | |
| Measure [Axis]: 1 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Revenue growth | | |
| Measure [Axis]: 2 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Product revenues | | |
| Measure [Axis]: 3 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Year-end cash and cash equivalents | | |
| PEO [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | $ (19,472,543) | $ (45,816,126) | $ 104,205,901 |
| PEO [Member] | Stock Awards Adjustments [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (18,545,040) | (13,672,864) | (7,160,000) |
| PEO [Member] | Equity Awards Granted During the Year, Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 13,913,094 | 3,708,060 | 27,099,276 |
| PEO [Member] | Equity Awards Granted in Prior Years, Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (10,827,207) | (36,638,677) | 66,533,031 |
| PEO [Member] | Equity Awards Granted During the Year, Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | 0 | 0 |
| PEO [Member] | Equity Awards Granted in Prior Years, Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (4,013,390) | 787,355 | 17,733,594 |
| Non-PEO NEO [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (3,380,118) | (11,130,384) | 19,243,934 |
| Non-PEO NEO [Member] | Stock Awards Adjustments [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (6,059,426) | (5,279,647) | (2,837,222) |
| Non-PEO NEO [Member] | Equity Awards Granted During the Year, Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 4,783,831 | 1,299,614 | 4,659,848 |
| Non-PEO NEO [Member] | Equity Awards Granted in Prior Years, Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (1,408,060) | (7,338,300) | 16,035,472 |
| Non-PEO NEO [Member] | Equity Awards Granted During the Year, Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | 259,613 | 0 |
| Non-PEO NEO [Member] | Equity Awards Granted in Prior Years, Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | $ (696,463) | $ (71,664) | $ 1,385,836 |
