Shareholder Report |
6 Months Ended | |||||||||
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May 31, 2026
USD ($)
shares
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| Shareholder Report [Line Items] | ||||||||||
| Document Type | N-CSRS | |||||||||
| Amendment Flag | false | |||||||||
| Registrant Name | Fidelity Phillips Street Trust | |||||||||
| Entity Central Index Key | 0000278001 | |||||||||
| Entity Investment Company Type | N-1A | |||||||||
| Document Period End Date | May 31, 2026 | |||||||||
| Fidelity Government Cash Reserves | ||||||||||
| Shareholder Report [Line Items] | ||||||||||
| Fund Name | Fidelity® Government Cash Reserves | |||||||||
| Class Name | Fidelity® Government Cash Reserves | |||||||||
| Trading Symbol | FDRXX | |||||||||
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains information about Fidelity® Government Cash Reserves for the period December 1, 2025 to May 31, 2026. | |||||||||
| 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)
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| Expenses Paid, Amount | $ 18 | |||||||||
| Expense Ratio, Percent | 0.35% | |||||||||
| Net Assets | $ 246,582,952,605 | |||||||||
| Holdings Count | shares | 738 | |||||||||
| Additional Fund Statistics [Text Block] | Key Fund Statistics
(as of May 31, 2026)
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| Holdings [Text Block] | EFFECTIVE MATURITY DIVERSIFICATION (% of Fund's net assets) Days 1-7 61.1 8-30 5.5 31-60 9.8 61-90 5.5 91-180 12.5 >180 7.7 Repurchase Agreements 41.6 U.S. Treasury Obligations 30.9 U.S. Government Agency - Debt 29.9 ASSET ALLOCATION (% of Fund's net assets) Repurchase Agreements - 41.6 U.S. Treasury Obligations - 30.9 U.S. Government Agency - Debt - 29.9 Net Other Assets (Liabilities) - (2.4)% |