Label

Element

Value

Prospectus:

rr_ProspectusTable

Document Type

dei_DocumentType

Other

Document Period End Date

dei_DocumentPeriodEndDate

Oct. 30, 2015

Registrant Name

dei_EntityRegistrantName

Calvert Fund

Central Index Key

dei_EntityCentralIndexKey

0000701039

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Oct. 30, 2015

Document Effective Date

dei_DocumentEffectiveDate

Oct. 30, 2015

Prospectus Date

rr_ProspectusDate

Jan. 31, 2015

Calvert High Yield Bond Fund

Prospectus:

rr_ProspectusTable

Supplement [Text Block]

cik0000701039_SupplementTextBlock

CALVERT HIGH YIELD BOND FUND

CALVERT GREEN BOND FUND

Supplement to

Calvert Income Funds Prospectus (Class A, B, C and Y)

dated January 31, 2015

Calvert Income Funds Prospectus (Class I)

dated January 31, 2015

Date of Supplement: October 30, 2015

The information in this Supplement updates information in the Prospectus, supersedes any contrary information in the Prospectus or any prior supplement, and should be read in conjunction with the Prospectus.

Effective immediately, Calvert High Yield Bond Fund and Calvert Green Bond Fund (each a “Fund”) have adopted the Calvert Principles for Responsible Investment. Furthermore, effective November 30, 2015,each Fund has approved the addition of certain portfolio managers to the Funds to better reflect a team approach to portfolio management.

Responsible Investment Principles

Effective immediately, each Prospectus is hereby amended as follows:

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The last paragraph under “Investments, Risks and Performance – Principal Investment Strategies” in the Fund Summary for each Fund is deleted and replaced with the following:

Responsible Investing. In conjunction with Calvert’s financial analysis, Calvert’s comprehensive responsible investment principles guide our investment research processes and decision-making. The principles are applied across industries and to specific companies in order to inform our view of risk and opportunity factors that may affect investment performance.

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

Under "Investments, Risks and Performance – Principal Risks” in the Fund Summary for each Fund, delete “Tobacco Exclusion Risk” and insert the following:

Responsible Investing Risk. Investing primarily in responsible investments carries the risk that, under certain market conditions, the Fund may underperform funds that invest in a broader array of investments. The application of responsible investment principles may affect the Fund’s exposure to certain sectors or types of investments and may impact the Fund’s relative investment performance, depending on whether such sectors or investments are in or out of favor in the market.