| Label                                            | **Element**              | Value                                                                                                                                                                                                                        |
|--------------------------------------------------|--------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| **Risk/Return:**                                 | rr_RiskReturnAbstract    |                                                                                                                                                                                                                         |
| Registrant Name                                  | dei_EntityRegistrantName | Fidelity Rutland Square Trust II                                                                                                                                                                                             |
| Prospectus Date                                  | rr_ProspectusDate        | Jul. 30,  2015                                                                                                                                                                                                               |
| F | Strategic Advisers Growth Multi-Manager Fund |                          |                                                                                                                                                                                                                         |
| **Risk/Return:**                                 | rr_RiskReturnAbstract    |                                                                                                                                                                                                                         |
| Supplement [Text Block]                          | frst_SupplementTextBlock | **Supplement to the Strategic Advisers® Growth Multi-Manager Fund Class F July 30, 2015 Prospectus***Effective October 1, 2015, the fund changed its classification from a non-diversified fund to a diversified fund.* |

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| X                                                                                                                                 |
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