| Cover | Feb. 03, 2020 |
| Entity Information [Line Items] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Feb. 3, 2020 |
| Entity File Number | 1-13130 |
| Entity Registrant Name | LIBERTY PROPERTY TRUST |
| Entity Central Index Key | 0000921112 |
| Entity Tax Identification Number | 23-7768996 |
| Entity Incorporation, State or Country Code | MD |
| Entity Address, Address Line One | 650 E. Swedesford Road |
| Entity Address, City or Town | Wayne |
| Entity Address, State or Province | PA |
| Entity Address, Postal Zip Code | 19087 |
| City Area Code | 610 |
| Local Phone Number | 648-1700 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Shares of Beneficial Interest, $0.001 par value |
| Trading Symbol | LPT |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Liberty Property Limited Partnership [Member] | |
| Entity Information [Line Items] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Feb. 3, 2020 |
| Entity File Number | 1-13132 |
| Entity Registrant Name | LIBERTY PROPERTY LIMITED PARTNERSHIP |
| Entity Central Index Key | 0000921113 |
| Entity Tax Identification Number | 23-2766549 |
| Entity Incorporation, State or Country Code | PA |
| Entity Address, Address Line One | 650 E. Swedesford Road |
| Entity Address, City or Town | Wayne |
| Entity Address, State or Province | PA |
| Entity Address, Postal Zip Code | 19087 |
| City Area Code | 610 |
| Local Phone Number | 648-1700 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
