v3.25.2
Shareholder Report
 6 Months Ended
May 31, 2025
USD ($)
shares
Shareholder Report [Line Items]  
Document Type N-CSRS
Amendment Flag false
Registrant Name Fidelity Concord Street Trust
Entity Central Index Key 0000819118
Entity Investment Company Type N-1A
Document Period End Date May 31, 2025
Fidelity Nasdaq Composite Index Fund  
Shareholder Report [Line Items]  
Fund Name Fidelity® Nasdaq Composite Index® Fund
Class Name Fidelity® Nasdaq Composite Index® Fund
Trading Symbol FNCMX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains information about Fidelity® Nasdaq Composite Index® Fund for the period December 1, 2024 to May 31, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at fundresearch.fidelity.com/prospectus/sec. You can also request this information by contacting us at 1-800-544-8544 or by sending an e-mail to fidfunddocuments@fidelity.com.
Additional Information Phone Number 1-800-544-8544
Additional Information Email fidfunddocuments@fidelity.com
Additional Information Website fundresearch.fidelity.com/prospectus/sec
Expenses [Text Block] What were your Fund costs for the last six months?
(based on hypothetical $10,000 investment)
 
 
 
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
 
Fidelity® Nasdaq Composite Index® Fund 
$ 14 
0.29%
  
Expenses Paid, Amount $ 14
Expense Ratio, Percent 0.29%
Net Assets $ 18,473,815,196
Holdings Count | shares 2,719
Investment Company Portfolio Turnover 5.00%
Additional Fund Statistics [Text Block] Key Fund Statistics
(as of May 31, 2025)
 
KEY FACTS 
  
  
Fund Size
$18,473,815,196
  
Number of Holdings
2,719
  
Portfolio Turnover
5%
  
Holdings [Text Block]       MARKET SECTORS (% of Fund's net assets)     Information Technology 49.4   Communication Services 15.1   Consumer Discretionary 14.9   Health Care 5.4   Industrials 4.5   Financials 3.9   Consumer Staples 3.6   Utilities 0.9   Materials 0.9   Real Estate 0.8   Energy 0.5     Common Stocks 99.9 Preferred Stocks 0.0 Short-Term Investments and Net Other Assets (Liabilities) 0.1 ASSET ALLOCATION (% of Fund's net assets)     Common Stocks - 99.9                       Preferred Stocks - 0.0                     Short-Term Investments and Net Other Assets (Liabilities) - 0.1   United States 96.2 Canada 1.0 China 0.7 Netherlands 0.6 Brazil 0.5 Israel 0.3 United Kingdom 0.3 Kazakhstan 0.1 Hong Kong 0.1 Others 0.2 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets)     United States - 96.2                       Canada - 1.0                               China - 0.7                                Netherlands - 0.6                          Brazil - 0.5                               Israel - 0.3                               United Kingdom - 0.3                       Kazakhstan - 0.1                           Hong Kong - 0.1                            Others - 0.2                                  
Largest Holdings [Text Block] TOP HOLDINGS (% of Fund's net assets)     Microsoft Corp 11.0   NVIDIA Corp 10.6   Apple Inc 9.6   Amazon.com Inc 7.0   Meta Platforms Inc Class A 4.5   Broadcom Inc 3.7   Tesla Inc 3.5   Alphabet Inc Class A 3.3   Alphabet Inc Class C 3.0   Netflix Inc 1.7     57.9