v3.26.1
Shareholder Report
 6 Months Ended
Jun. 30, 2026
USD ($)
Holding
Shareholder Report [Line Items]  
Document Type N-CSRS
Amendment Flag false
Registrant Name TAX-MANAGED GROWTH PORTFOLIO
Entity Central Index Key 0001002667
Entity Investment Company Type N-1A
Document Period End Date Jun. 30, 2026
Shareholder Report Annual or Semi-Annual Semi-Annual Shareholder Report
C000014300  
Shareholder Report [Line Items]  
Fund Name Tax-Managed Growth 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 Growth Portfolio (the "Fund") for the period of January 1, 2026 to June 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 Growth Fund 1.1. 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 Growth Portfolio
$22
0.42%Footnote Reference1
Footnote Description
Footnote1
 Annualized
Expenses Paid, Amount $ 22
Expense Ratio, Percent 0.42% [1]
AssetsNet $ 7,004,218,282
Holdings Count | Holding 107
InvestmentCompanyPortfolioTurnover 11.00%
Additional Fund Statistics [Text Block]

Key Fund Statistics

Table Summary
Total Net Assets
$7,004,218,282
# of Portfolio Holdings
107
Portfolio Turnover Rate
11%
Holdings [Text Block]

Sector Allocation (% of total investments)

Group By Asset Type Chart
Table Summary
Value
Value
Short-Term Investments
0.4%
Utilities
0.7%
Materials
1.2%
Energy
2.2%
Consumer Staples
3.8%
Health Care
8.2%
Industrials
9.8%
Consumer Discretionary
10.6%
Communication Services
12.8%
Financials
13.6%
Information Technology
36.7%
Largest Holdings [Text Block]

Top Ten Holdings (% of total investments)Footnote Referencea

Table Summary
NVIDIA Corp.
9.1%
Amazon.com, Inc.
5.4%
Apple, Inc.
4.9%
Alphabet, Inc., Class A
4.1%
Alphabet, Inc., Class C
4.1%
Microsoft Corp.
3.5%
Meta Platforms, Inc., Class A
3.4%
Broadcom, Inc.
3.3%
Advanced Micro Devices, Inc.
2.7%
Berkshire Hathaway, Inc., Class B
2.5%
Total
43.0%
Footnote Description
Footnotea
 Excluding cash equivalents
Material Fund Change [Text Block]
Updated Prospectus Phone Number 1-800-262-1122
[1] Annualized