v3.26.1
Shareholder Report
 6 Months Ended
Apr. 30, 2026
USD ($)
Holding
Shareholder Report [Line Items]  
Document Type N-CSRS
Amendment Flag false
Registrant Name TAX MANAGED SMALL CAP PORTFOLIO
Entity Central Index Key 0001122006
Entity Investment Company Type N-1A
Document Period End Date Apr. 30, 2026
Shareholder Report Annual or Semi-Annual Semi-Annual Shareholder Report
C000014304  
Shareholder Report [Line Items]  
Fund Name Tax-Managed Small-Cap Portfolio
No Trading Symbol [Flag] true
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about the Tax-Managed Small-Cap Portfolio (the "Fund") for the period of November 1, 2025 to April 30, 2026.
Additional Information [Text Block] You can find additional information about the Fund at www.eatonvance.com/open-end-mutual-fund-documents.php and selecting Eaton Vance Tax-Managed Small-Cap Fund. You can also request this information by contacting us at 1-800-262-1122.
Additional Information Phone Number 1-800-262-1122
Additional Information Website <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: 12.8px; margin: 0px; overflow: visible; text-align: left; text-align-last: auto; white-space-collapse: preserve-breaks;">www.eatonvance.com/open-end-mutual-fund-documents.php</span>
Expenses [Text Block]

What were the Fund costs for the last six months?

(based on a hypothetical $10,000 investment)

Table Summary
Fund Name
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Tax-Managed Small-Cap Portfolio
$36
0.71%Footnote Reference1
Footnote Description
Footnote1
 Annualized
Expenses Paid, Amount $ 36
Expense Ratio, Percent 0.71% [1]
AssetsNet $ 183,136,485
Holdings Count | Holding 66
InvestmentCompanyPortfolioTurnover 28.00%
Additional Fund Statistics [Text Block]

Key Fund Statistics

Table Summary
Total Net Assets
$183,136,485
# of Portfolio Holdings
66
Portfolio Turnover Rate
28%
Holdings [Text Block]

Sector Allocation (% of total investments)

Group By Asset Type Chart
Table Summary
Value
Value
Energy
1.3%
Utilities
2.5%
Short-Term Investments
3.1%
Consumer Staples
3.4%
Health Care
4.9%
Materials
5.8%
Real Estate
6.9%
Information Technology
12.0%
Consumer Discretionary
14.9%
Financials
19.6%
Industrials
25.6%
Largest Holdings [Text Block]

Top Ten Holdings (% of total investments)Footnote Referencea

Table Summary
CSW Industrials, Inc.
3.5%
Community Financial System, Inc.
2.9%
Diodes, Inc.
2.9%
Franklin Electric Co., Inc.
2.9%
Dorman Products, Inc.
2.8%
Southstate Bank Corp.
2.8%
Aramark
2.6%
Essential Properties Realty Trust, Inc.
2.6%
IDACORP, Inc.
2.5%
Valvoline, Inc.
2.5%
Total
28.0%
Footnote Description
Footnotea
 Excluding cash equivalents
Material Fund Change [Text Block]
Updated Prospectus Phone Number 1-800-262-1122
[1] Annualized