Shareholder Report |
6 Months Ended | ||||||||||||
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Jun. 30, 2026
USD ($)
shares
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| Shareholder Report [Line Items] | |||||||||||||
| Document Type | N-CSRS | ||||||||||||
| Amendment Flag | false | ||||||||||||
| Registrant Name | Fidelity Central Investment Portfolios II LLC | ||||||||||||
| Entity Central Index Key | 0001401097 | ||||||||||||
| Entity Investment Company Type | N-1A | ||||||||||||
| Document Period End Date | Jun. 30, 2026 | ||||||||||||
| Fidelity International Credit Central Fund | |||||||||||||
| Shareholder Report [Line Items] | |||||||||||||
| Fund Name | Fidelity® International Credit Central Fund | ||||||||||||
| Class Name | Fidelity® International Credit Central Fund | ||||||||||||
| No Trading Symbol Flag | true | ||||||||||||
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains information about Fidelity® International Credit Central Fund for the period January 1, 2026 to June 30, 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. | ||||||||||||
| Additional Information Phone Number | 1-800-544-8544 | ||||||||||||
| 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)
A Amount represents less than $.50
B Amount represents less than 0.005%
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| Expenses Paid, Amount | $ 0 | ||||||||||||
| Expense Ratio, Percent | 0.00% | ||||||||||||
| Net Assets | $ 103,840,375 | ||||||||||||
| Holdings Count | shares | 283 | ||||||||||||
| Investment Company Portfolio Turnover | 38.00% | ||||||||||||
| Additional Fund Statistics [Text Block] | Key Fund Statistics
(as of June 30, 2026)
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| Holdings [Text Block] | U.S. Government and U.S. Government Agency Obligations 18.6 AAA 10.0 AA 0.2 A 16.1 BBB 31.7 BB 5.2 B 1.8 CCC,CC,C 0.1 Not Rated 9.7 Short-Term Investments and Net Other Assets (Liabilities) 6.6 QUALITY DIVERSIFICATION (% of Fund's net assets) U.S. Government and U.S. Government Agency Obligations - 18.6 AAA - 10.0 AA - 0.2 A - 16.1 BBB - 31.7 BB - 5.2 B - 1.8 CCC,CC,C - 0.1 Not Rated - 9.7 Short-Term Investments and Net Other Assets (Liabilities) - 6.6 We have used ratings from Moody's Investors Service, Inc. Where Moody's® ratings are not available, we have used S&P® ratings. All ratings are as of the date indicated and do not reflect subsequent changes. Corporate Bonds 60.5 U.S. Treasury Obligations 18.6 Foreign Government and Government Agency Obligations 9.4 Preferred Securities 4.9 Short-Term Investments and Net Other Assets (Liabilities) 6.6 ASSET ALLOCATION (% of Fund's net assets) Corporate Bonds - 60.5 U.S. Treasury Obligations - 18.6 Foreign Government and Government Agency Obligations - 9.4 Preferred Securities - 4.9 Short-Term Investments and Net Other Assets (Liabilities) - 6.6 United States 31.3 United Kingdom 18.9 Germany 10.8 France 5.9 Canada 5.0 Switzerland 4.6 Multi-national 4.1 Japan 3.2 Luxembourg 2.6 Others 13.6 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets) United States - 31.3 United Kingdom - 18.9 Germany - 10.8 France - 5.9 Canada - 5.0 Switzerland - 4.6 Multi-national - 4.1 Japan - 3.2 Luxembourg - 2.6 Others - 13.6 | ||||||||||||
| Largest Holdings [Text Block] | TOP HOLDINGS(% of Fund's net assets) US Treasury Notes 13.7 US Treasury Bonds 4.9 European Union 3.2 KfW 3.0 Canadian Government 2.9 Japan Government 2.2 Credit Suisse Group AG 2.2 BNP Paribas SA 1.8 HSBC Holdings PLC 1.7 UBS Group AG 1.6 37.2 |