| Cover Page | Nov. 03, 2021 |
| Entity Information [Line Items] | |
| Entity Central Index Key | 0001075415 |
| Written Communications | false |
| Entity File Number | 001-15319 |
| Document Period End Date | Nov. 3, 2021 |
| Document Type | 8-K |
| Entity Registrant Name | DIVERSIFIED HEALTHCARE TRUST |
| Entity Tax Identification Number | 04-3445278 |
| Entity Incorporation, State or Country Code | MD |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Address, Address Line One | Two Newton Place, 255 Washington Street, Suite 300 |
| Title of 12(b) Security | Common Shares of Beneficial Interest |
| Entity Address, City or Town | Newton |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 02458-1634 |
| City Area Code | 617 |
| Local Phone Number | 796-8350 |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Trading Symbol | DHC |
| Security Exchange Name | NASDAQ |
| Senior Notes Due 2046 | |
| Entity Information [Line Items] | |
| Title of 12(b) Security | 6.25% Senior Notes due 2046 |
| Trading Symbol | DHCNL |
| Security Exchange Name | NASDAQ |
| Senior Notes Due 2042 | |
| Entity Information [Line Items] | |
| Title of 12(b) Security | 5.625% Senior Notes due 2042 |
| Trading Symbol | DHCNI |
| Security Exchange Name | NASDAQ |
