| Form N-CSR Cover | 6 Months Ended |
| Jun. 30, 2024 | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSRS |
| Amendment Flag | false |
| Registrant Name | T. ROWE PRICE INDEX TRUST, INC. |
| Entity Central Index Key | 0000858581 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Jun. 30, 2024 |
| Shareholder Report | 6 Months Ended |
| Jun. 30, 2024 USD ($) Holding | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSRS |
| Amendment Flag | false |
| Registrant Name | T. ROWE PRICE INDEX TRUST, INC. |
| Entity Central Index Key | 0000858581 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Jun. 30, 2024 |
| C000161837 | |
| Shareholder Report [Line Items] | |
| Fund Name | Small-Cap Index Fund |
| Class Name | Investor Class |
| Trading Symbol | TRSYX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about Small-Cap Index Fund (the "fund") for the period of January 1, 2024 to June 30, 2024. You can find the fund’s prospectus, financial information on Form N‑CSR (which includes required tax information for dividends), holdings, proxy voting information, and other information at www.troweprice.com/prospectus info troweprice.com |
| Shareholder Report Annual or Semi-Annual | Semi-Annual Shareholder Report |
| Additional Information [Text Block] | You can find the fund’s prospectus, financial information on Form N‑CSR (which includes required tax information for dividends), holdings, proxy voting information, and other information at www.troweprice.com/prospectus info troweprice.com |
| Material Fund Change Notice [Text Block] | |
| Additional Information Phone Number | 1‑800‑638‑5660 |
| Additional Information Email | info@troweprice.com</span>" id="sjs-B20"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 13.3333px; font-weight: 400; grid-area: auto; line-height: 17.3333px; margin: 0px; overflow: visible; text-align: justify;">info@troweprice.com</span> |
| Additional Information Website | www.troweprice.com/prospectus</span>" id="sjs-B21"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 13.3333px; font-weight: 700; grid-area: auto; line-height: 17.3333px; margin: 0px; overflow: visible; text-align: justify;">www.troweprice.com/prospectus</span> |
| Expenses [Text Block] | What were the fund costs for the last six months? Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Small-Cap Index Fund - Investor Class $15 0.29% |
| Expenses Paid, Amount | $ 15 |
| Expense Ratio, Percent | 0.29% |
| Updated Performance Information Location [Text Block] | If you invest directly with T. Rowe Price, you can elect to receive future shareholder reports or other important documents through electronic delivery by enrolling at www.troweprice.com/paperless |
| AssetsNet | $ 167,915,000 |
| Holdings Count | Holding | 2,009 |
| InvestmentCompanyPortfolioTurnover | 19.90% |
| Additional Fund Statistics [Text Block] | What are some fund statistics? Fund Statistics Total Net Assets (000s) $167,915 Number of Portfolio Holdings 2,009 |
| Additional Fund Statistics Significance or Limits [Text Block] | Portfolio Turnover Rate 19.9% |
| Holdings [Text Block] | Sector Allocation Health Care 17.3 % Industrials & Business Services 17.2 Financials 17.0 Information Technology 13.3 Consumer Discretionary 10.1 Energy 6.6 Real Estate 5.9 Materials 4.6 Utilities 2.8 Other 5.2 |
| Largest Holdings [Text Block] | Top Ten Holdings Insmed 0.4 % FTAI Aviation 0.4 Abercrombie & Fitch 0.4 Fabrinet 0.4 Sprouts Farmers Market 0.3 Vaxcyte 0.3 Applied Industrial Technologies 0.3 Fluor 0.3 HealthEquity 0.3 SPS Commerce 0.3 |
| Material Fund Change [Text Block] | |
| Updated Prospectus Web Address | www.troweprice.com/paperless</span>" id="sjs-B34"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 10.6667px; font-weight: 400; grid-area: auto; line-height: 13.8667px; margin: 0px; overflow: visible; text-align: justify;">www.troweprice.com/paperless</span> |
| C000161838 | |
| Shareholder Report [Line Items] | |
| Fund Name | Small-Cap Index Fund |
| Class Name | I Class |
| Trading Symbol | TRCSX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about Small-Cap Index Fund (the "fund") for the period of January 1, 2024 to June 30, 2024. You can find the fund’s prospectus, financial information on Form N‑CSR (which includes required tax information for dividends), holdings, proxy voting information, and other information at www.troweprice.com/prospectus info troweprice.com |
| Shareholder Report Annual or Semi-Annual | Semi-Annual Shareholder Report |
| Additional Information [Text Block] | You can find the fund’s prospectus, financial information on Form N‑CSR (which includes required tax information for dividends), holdings, proxy voting information, and other information at www.troweprice.com/prospectus info troweprice.com |
| Material Fund Change Notice [Text Block] | |
| Additional Information Phone Number | 1‑800‑638‑5660 |
| Additional Information Email | info@troweprice.com</span>" id="sjs-B45"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 13.3333px; font-weight: 400; grid-area: auto; line-height: 17.3333px; margin: 0px; overflow: visible; text-align: justify;">info@troweprice.com</span> |
| Additional Information Website | www.troweprice.com/prospectus</span>" id="sjs-B46"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 13.3333px; font-weight: 700; grid-area: auto; line-height: 17.3333px; margin: 0px; overflow: visible; text-align: justify;">www.troweprice.com/prospectus</span> |
| Expenses [Text Block] | What were the fund costs for the last six months? Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Small-Cap Index Fund - I Class $7 0.14% |
| Expenses Paid, Amount | $ 7 |
| Expense Ratio, Percent | 0.14% |
| Updated Performance Information Location [Text Block] | If you invest directly with T. Rowe Price, you can elect to receive future shareholder reports or other important documents through electronic delivery by enrolling at www.troweprice.com/paperless |
| AssetsNet | $ 167,915,000 |
| Holdings Count | Holding | 2,009 |
| InvestmentCompanyPortfolioTurnover | 19.90% |
| Additional Fund Statistics [Text Block] | What are some fund statistics? Fund Statistics Total Net Assets (000s) $167,915 Number of Portfolio Holdings 2,009 |
| Additional Fund Statistics Significance or Limits [Text Block] | Portfolio Turnover Rate 19.9% |
| Holdings [Text Block] | Sector Allocation Health Care 17.3 % Industrials & Business Services 17.2 Financials 17.0 Information Technology 13.3 Consumer Discretionary 10.1 Energy 6.6 Real Estate 5.9 Materials 4.6 Utilities 2.8 Other 5.2 |
| Largest Holdings [Text Block] | Top Ten Holdings Insmed 0.4 % FTAI Aviation 0.4 Abercrombie & Fitch 0.4 Fabrinet 0.4 Sprouts Farmers Market 0.3 Vaxcyte 0.3 Applied Industrial Technologies 0.3 Fluor 0.3 HealthEquity 0.3 SPS Commerce 0.3 |
| Material Fund Change [Text Block] | |
| Updated Prospectus Web Address | www.troweprice.com/paperless</span>" id="sjs-B59"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 10.6667px; font-weight: 400; grid-area: auto; line-height: 13.8667px; margin: 0px; overflow: visible; text-align: justify;">www.troweprice.com/paperless</span> |
| C000219329 | |
| Shareholder Report [Line Items] | |
| Fund Name | Small-Cap Index Fund |
| Class Name | Z Class |
| Trading Symbol | TRZIX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about Small-Cap Index Fund (the "fund") for the period of January 1, 2024 to June 30, 2024. You can find the fund’s prospectus, financial information on Form N‑CSR (which includes required tax information for dividends), holdings, proxy voting information, and other information at www.troweprice.com/prospectus info troweprice.com |
| Shareholder Report Annual or Semi-Annual | Semi-Annual Shareholder Report |
| Additional Information [Text Block] | You can find the fund’s prospectus, financial information on Form N‑CSR (which includes required tax information for dividends), holdings, proxy voting information, and other information at www.troweprice.com/prospectus info troweprice.com |
| Material Fund Change Notice [Text Block] | |
| Additional Information Phone Number | 1‑800‑638‑5660 |
| Additional Information Email | info@troweprice.com</span>" id="sjs-B70"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 13.3333px; font-weight: 400; grid-area: auto; line-height: 17.3333px; margin: 0px; overflow: visible; text-align: justify;">info@troweprice.com</span> |
| Additional Information Website | www.troweprice.com/prospectus</span>" id="sjs-B71"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 13.3333px; font-weight: 700; grid-area: auto; line-height: 17.3333px; margin: 0px; overflow: visible; text-align: justify;">www.troweprice.com/prospectus</span> |
| Expenses [Text Block] | What were the fund costs for the last six months? Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Small-Cap Index Fund - Z Class $0 0.00% |
| Expenses Paid, Amount | $ 0 |
| Expense Ratio, Percent | 0% |
| Updated Performance Information Location [Text Block] | If you invest directly with T. Rowe Price, you can elect to receive future shareholder reports or other important documents through electronic delivery by enrolling at www.troweprice.com/paperless |
| AssetsNet | $ 167,915,000 |
| Holdings Count | Holding | 2,009 |
| InvestmentCompanyPortfolioTurnover | 19.90% |
| Additional Fund Statistics [Text Block] | What are some fund statistics? Fund Statistics Total Net Assets (000s) $167,915 Number of Portfolio Holdings 2,009 |
| Additional Fund Statistics Significance or Limits [Text Block] | Portfolio Turnover Rate 19.9% |
| Holdings [Text Block] | Sector Allocation Health Care 17.3 % Industrials & Business Services 17.2 Financials 17.0 Information Technology 13.3 Consumer Discretionary 10.1 Energy 6.6 Real Estate 5.9 Materials 4.6 Utilities 2.8 Other 5.2 |
| Largest Holdings [Text Block] | Top Ten Holdings Insmed 0.4 % FTAI Aviation 0.4 Abercrombie & Fitch 0.4 Fabrinet 0.4 Sprouts Farmers Market 0.3 Vaxcyte 0.3 Applied Industrial Technologies 0.3 Fluor 0.3 HealthEquity 0.3 SPS Commerce 0.3 |
| Material Fund Change [Text Block] | |
| Updated Prospectus Web Address | www.troweprice.com/paperless</span>" id="sjs-B84"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 10.6667px; font-weight: 400; grid-area: auto; line-height: 13.8667px; margin: 0px; overflow: visible; text-align: justify;">www.troweprice.com/paperless</span> |
| Shareholder Report, Holdings (Details) | Jun. 30, 2024 |
| C000161837 | Insmed | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000161837 | FTAI Aviation | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000161837 | Abercrombie & Fitch | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000161837 | Fabrinet | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000161837 | Sprouts Farmers Market | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000161837 | Vaxcyte | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000161837 | Applied Industrial Technologies | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000161837 | Fluor | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000161837 | HealthEquity | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000161837 | SPS Commerce | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000161837 | Health Care | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 17.30% |
| C000161837 | Industrials & Business Services | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 17.20% |
| C000161837 | Financials | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 17% |
| C000161837 | Information Technology | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 13.30% |
| C000161837 | Consumer Discretionary | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.10% |
| C000161837 | Energy | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.60% |
| C000161837 | Real Estate | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.90% |
| C000161837 | Materials | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.60% |
| C000161837 | Utilities | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| C000161838 | Insmed | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000161838 | FTAI Aviation | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000161838 | Abercrombie & Fitch | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000161838 | Fabrinet | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000161838 | Sprouts Farmers Market | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000161838 | Vaxcyte | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000161838 | Applied Industrial Technologies | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000161838 | Fluor | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000161838 | HealthEquity | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000161838 | SPS Commerce | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000161838 | Health Care | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 17.30% |
| C000161838 | Industrials & Business Services | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 17.20% |
| C000161838 | Financials | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 17% |
| C000161838 | Information Technology | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 13.30% |
| C000161838 | Consumer Discretionary | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.10% |
| C000161838 | Energy | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.60% |
| C000161838 | Real Estate | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.90% |
| C000161838 | Materials | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.60% |
| C000161838 | Utilities | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| C000219329 | Insmed | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000219329 | FTAI Aviation | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000219329 | Abercrombie & Fitch | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000219329 | Fabrinet | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000219329 | Sprouts Farmers Market | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000219329 | Vaxcyte | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000219329 | Applied Industrial Technologies | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000219329 | Fluor | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000219329 | HealthEquity | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000219329 | SPS Commerce | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000219329 | Health Care | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 17.30% |
| C000219329 | Industrials & Business Services | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 17.20% |
| C000219329 | Financials | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 17% |
| C000219329 | Information Technology | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 13.30% |
| C000219329 | Consumer Discretionary | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.10% |
| C000219329 | Energy | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.60% |
| C000219329 | Real Estate | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.90% |
| C000219329 | Materials | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.60% |
| C000219329 | Utilities | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
