XML 81 R67.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Real Estate and Accumulated Depreciation - Estimated Useful Lives of Assets (Detail) | 12 Months Ended
--- | ---
Dec. 31, 2018
Base building | Minimum |
Property Plant and Equipment Estimated Useful Lives [Line Items] |
Estimated useful life | 35 years
Base building | Maximum |
Property Plant and Equipment Estimated Useful Lives [Line Items] |
Estimated useful life | 50 years
Building components | Maximum |
Property Plant and Equipment Estimated Useful Lives [Line Items] |
Estimated useful life | 20 years

X
- Definition Property Plant and Equipment Estimated Useful Lives [Line Items] + References No definition available. + Details
Name: | bfs_PropertyPlantAndEquipmentEstimatedUsefulLivesLineItems
Namespace Prefix: | bfs_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment. + References No definition available. + Details
Name: | us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=bfs_BuildingComponentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |