| Document and Entity Information | Oct. 29, 2020 |
| Cover [Abstract] | |
| Entity Registrant Name | RESMED INC |
| Entity Address, Country | US |
| Amendment Flag | true |
| Entity Central Index Key | 0000943819 |
| Document Type | 8-K/A |
| Document Period End Date | Oct. 29, 2020 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-15317 |
| Entity Tax Identification Number | 98-0152841 |
| Entity Address, Address Line One | 9001 Spectrum Center Blvd. |
| Entity Address, City or Town | San Diego |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 92123 |
| City Area Code | (858) |
| Local Phone Number | 836-5000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $0.004 par value |
| Trading Symbol | RMD |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Amendment Description | This Form 8-K/A is being filed to update the disclosure under Item 8.01 of our Current Report on Form 8-K of ResMed Inc. filed with the Securities and Exchange Commission on October 29, 2020 to revise the ex-dividend date for the previously-announced cash dividend. |
