| Form N-CSR Cover | 12 Months Ended |
| Jul. 31, 2024 | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSR |
| Amendment Flag | false |
| Registrant Name | ETFis Series Trust I |
| Entity Central Index Key | 0001559109 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Jul. 31, 2024 |
| Shareholder Report | 12 Months Ended | 106 Months Ended |
| Jul. 31, 2024 USD ($) Holding | Jul. 31, 2024 USD ($) Holding | |
| Shareholder Report [Line Items] | ||
| Document Type | N-CSR | |
| Amendment Flag | false | |
| Registrant Name | ETFis Series Trust I | |
| Entity Central Index Key | 0001559109 | |
| Entity Investment Company Type | N-1A | |
| Document Period End Date | Jul. 31, 2024 | |
| C000156214 | ||
| Shareholder Report [Line Items] | ||
| Fund Name | Virtus Reaves Utilities ETF | |
| Class Name | UTES | |
| No Trading Symbol [Flag] | true | |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about the Virtus Reaves Utilities ETF ("Fund") for the period of August 1, 2023 to July 31, 2024. | |
| Shareholder Report Annual or Semi-Annual | Annual Shareholder Report | |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.virtus.com/investor-resources/etf-documents | |
| Additional Information Phone Number | 1-888-383-0553 | |
| Additional Information Website | https://www.virtus.com/investor-resources/etf-documents</span>" id="sjs-B19"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 18px; margin: 0px; overflow: visible; text-align: left;">https://www.virtus.com/investor-resources/etf-documents</span> | |
| Expenses [Text Block] | What were the Fund costs for the period? (Based on a hypothetical $10,000 investment) Fund Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Virtus Reaves Utilities ETF $54 0.49% | |
| Expenses Paid, Amount | $ 54 | |
| Expense Ratio, Percent | 0.49% | |
| Factors Affecting Performance [Text Block] | Commentary by Reaves Asset Management For the fiscal year ended July 31, 2024, the Fund at NAV returned 19.12%. For the same period, the S&P 500 ® ® | |
| Performance Past Does Not Indicate Future [Text] | Performance data quoted represents past performance. | |
| Average Annual Return [Table Text Block] | ANNUAL AVERAGE TOTAL RETURNS 1 Year 5 Years Since Inception 9/23/15 Virtus Reaves Utilities ETF - NAV 19.12 9.41 11.73 Virtus Reaves Utilities ETF - Market 19.24 9.41 11.74 S&P 500 ® 22.15 15.00 14.60 S&P 500 ® 12.36 7.57 10.03 | |
| Performance Inception Date | Sep. 23, 2015 | |
| No Deduction of Taxes [Text Block] | The above table and graph do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of shares. | |
| AssetsNet | $ 110,947,656 | $ 110,947,656 |
| Holdings Count | Holding | 19 | 19 |
| Advisory Fees Paid, Amount | $ 292,253 | |
| InvestmentCompanyPortfolioTurnover | 51% | |
| Additional Fund Statistics [Text Block] | KEY FUND STATISTIC (as of July 31, 2024) Fund net assets $110,947,656 Total number of portfolio holdings 19 Total advisory fees paid $292,253 Portfolio turnover rate 51% | |
| Holdings [Text Block] | ASSET ALLOCATION Footnote Reference Utilities 100.00% Footnote Description Footnote (1) Percentage of total investments as of July 31, 2024. | |
| Material Fund Change [Text Block] |
| Shareholder Report, Line Graph (Details) - USD ($) | Sep. 23, 2015 | Jul. 31, 2024 | Jun. 30, 2024 | May 31, 2024 | Apr. 30, 2024 | Mar. 31, 2024 | Feb. 29, 2024 | Jan. 31, 2024 | Dec. 31, 2023 | Nov. 30, 2023 | Oct. 31, 2023 | Sep. 30, 2023 | Aug. 31, 2023 | Jul. 31, 2023 | Jun. 30, 2023 | May 31, 2023 | Apr. 30, 2023 | Mar. 31, 2023 | Feb. 28, 2023 | Jan. 31, 2023 | Dec. 31, 2022 | Nov. 30, 2022 | Oct. 31, 2022 | Sep. 30, 2022 | Aug. 31, 2022 | Jul. 31, 2022 | Jun. 30, 2022 | May 31, 2022 | Apr. 30, 2022 | Mar. 31, 2022 | Feb. 28, 2022 | Jan. 31, 2022 | Dec. 31, 2021 | Nov. 30, 2021 | Oct. 31, 2021 | Sep. 30, 2021 | Aug. 31, 2021 | Jul. 31, 2021 | Jun. 30, 2021 | May 31, 2021 | Apr. 30, 2021 | Mar. 31, 2021 | Feb. 28, 2021 | Jan. 31, 2021 | Dec. 31, 2020 | Nov. 30, 2020 | Oct. 31, 2020 | Sep. 30, 2020 | Aug. 31, 2020 | Jul. 31, 2020 | Jun. 30, 2020 | May 31, 2020 | Apr. 30, 2020 | Mar. 31, 2020 | Feb. 29, 2020 | Jan. 31, 2020 | Dec. 31, 2019 | Nov. 30, 2019 | Oct. 31, 2019 | Sep. 30, 2019 | Aug. 31, 2019 | Jul. 31, 2019 | Jun. 30, 2019 | May 31, 2019 | Apr. 30, 2019 | Mar. 31, 2019 | Feb. 28, 2019 | Jan. 31, 2019 | Dec. 31, 2018 | Nov. 30, 2018 | Oct. 31, 2018 | Sep. 30, 2018 | Aug. 31, 2018 | Jul. 31, 2018 | Jun. 30, 2018 | May 31, 2018 | Apr. 30, 2018 | Mar. 31, 2018 | Feb. 28, 2018 | Jan. 31, 2018 | Dec. 31, 2017 | Nov. 30, 2017 | Oct. 31, 2017 | Sep. 30, 2017 | Aug. 31, 2017 | Jul. 31, 2017 | Jun. 30, 2017 | May 31, 2017 | Apr. 30, 2017 | Mar. 31, 2017 | Feb. 28, 2017 | Jan. 31, 2017 | Dec. 31, 2016 | Nov. 30, 2016 | Oct. 31, 2016 | Sep. 30, 2016 | Aug. 31, 2016 | Jul. 31, 2016 | Jun. 30, 2016 | May 31, 2016 | Apr. 30, 2016 | Mar. 31, 2016 | Feb. 29, 2016 | Jan. 31, 2016 | Dec. 31, 2015 | Nov. 30, 2015 | Oct. 31, 2015 | Sep. 30, 2015 |
| C000156214 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Line Graph and Table Measure Name | Virtus Reaves Utilities ETF | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| S&P 500® Index | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Account Value | $ 10,000 | $ 33,446 | $ 33,043 | $ 31,899 | $ 30,392 | $ 31,686 | $ 30,698 | $ 29,142 | $ 28,661 | $ 27,415 | $ 25,121 | $ 25,661 | $ 26,945 | $ 27,381 | $ 26,529 | $ 24,885 | $ 24,777 | $ 24,396 | $ 23,532 | $ 24,121 | $ 22,695 | $ 24,082 | $ 22,808 | $ 21,099 | $ 23,240 | $ 24,228 | $ 22,182 | $ 24,178 | $ 24,134 | $ 26,440 | $ 25,493 | $ 26,280 | $ 27,714 | $ 26,525 | $ 26,710 | $ 24,961 | $ 26,179 | $ 25,407 | $ 24,817 | $ 24,251 | $ 24,083 | $ 22,863 | $ 21,903 | $ 21,315 | $ 21,533 | $ 20,736 | $ 18,690 | $ 19,200 | $ 19,959 | $ 18,620 | $ 17,626 | $ 17,283 | $ 16,497 | $ 14,623 | $ 16,683 | $ 18,180 | $ 18,187 | $ 17,654 | $ 17,036 | $ 16,674 | $ 16,368 | $ 16,632 | $ 16,396 | $ 15,316 | $ 16,356 | $ 15,719 | $ 15,420 | $ 14,940 | $ 13,832 | $ 15,204 | $ 14,901 | $ 15,994 | $ 15,904 | $ 15,402 | $ 14,849 | $ 14,758 | $ 14,411 | $ 14,356 | $ 14,730 | $ 15,294 | $ 14,466 | $ 14,307 | $ 13,881 | $ 13,565 | $ 13,290 | $ 13,250 | $ 12,983 | $ 12,902 | $ 12,723 | $ 12,594 | $ 12,579 | $ 12,099 | $ 11,874 | $ 11,644 | $ 11,228 | $ 11,436 | $ 11,434 | $ 11,418 | $ 11,012 | $ 10,984 | $ 10,790 | $ 10,748 | $ 10,065 | $ 10,079 | $ 10,605 | $ 10,775 | $ 10,743 | $ 9,908 |
| S&P 500® Utilities Index | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Account Value | $ 10,000 | $ 23,315 | $ 21,834 | $ 23,108 | $ 21,205 | $ 20,861 | $ 19,566 | $ 19,349 | $ 19,951 | $ 19,576 | $ 18,613 | $ 18,377 | $ 19,473 | $ 20,751 | $ 20,250 | $ 19,921 | $ 21,163 | $ 20,774 | $ 19,801 | $ 21,042 | $ 21,471 | $ 21,585 | $ 20,170 | $ 19,764 | $ 22,292 | $ 22,180 | $ 21,023 | $ 22,124 | $ 21,208 | $ 22,149 | $ 20,070 | $ 20,449 | $ 21,140 | $ 19,282 | $ 19,606 | $ 18,720 | $ 19,954 | $ 19,190 | $ 18,393 | $ 18,801 | $ 19,258 | $ 18,468 | $ 16,712 | $ 17,801 | $ 17,966 | $ 17,840 | $ 17,713 | $ 16,863 | $ 16,675 | $ 17,129 | $ 15,888 | $ 16,665 | $ 15,962 | $ 15,465 | $ 17,185 | $ 19,069 | $ 17,879 | $ 17,285 | $ 17,610 | $ 17,745 | $ 17,020 | $ 16,185 | $ 16,230 | $ 15,709 | $ 15,830 | $ 15,685 | $ 15,245 | $ 14,636 | $ 14,151 | $ 14,744 | $ 14,234 | $ 13,961 | $ 14,045 | $ 13,890 | $ 13,636 | $ 13,268 | $ 13,420 | $ 13,144 | $ 12,667 | $ 13,175 | $ 13,592 | $ 14,481 | $ 14,094 | $ 13,564 | $ 13,947 | $ 13,507 | $ 13,186 | $ 13,552 | $ 13,001 | $ 12,900 | $ 12,924 | $ 12,276 | $ 12,124 | $ 11,553 | $ 12,213 | $ 12,108 | $ 12,060 | $ 12,779 | $ 12,868 | $ 11,936 | $ 11,758 | $ 12,049 | $ 11,153 | $ 10,941 | $ 10,426 | $ 10,205 | $ 10,429 | $ 10,316 |
| Shareholder Report, Average Annual Return (Details) | 12 Months Ended | 60 Months Ended | 106 Months Ended | |
| Sep. 23, 2015 | Jul. 31, 2024 | Jul. 31, 2024 | Jul. 31, 2024 | |
| C000156214 | ||||
| Average Annual Return [Line Items] | ||||
| Line Graph and Table Measure Name | Virtus Reaves Utilities ETF | |||
| Without Sales Load [Member] | C000156214 | ||||
| Average Annual Return [Line Items] | ||||
| Average Annual Return, Percent | 19.12% | 9.41% | 11.73% | |
| S&P 500® Index | ||||
| Average Annual Return [Line Items] | ||||
| Average Annual Return, Percent | 22.15% | 15% | 14.60% | |
| S&P 500® Utilities Index | ||||
| Average Annual Return [Line Items] | ||||
| Average Annual Return, Percent | 12.36% | 7.57% | 10.03% | |
| Virtus Reaves Utilities ETF - Market | ||||
| Average Annual Return [Line Items] | ||||
| Average Annual Return, Percent | 19.24% | 9.41% | 11.74% |
| Shareholder Report, Holdings (Details) | Jul. 31, 2024 |
| C000156214 | Utilities | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 100% |
