Disclosure Of Fair Value Of Assets And Liabilities (Schedule Of Valuation Techniques And Significant Unobservable Assumptions) (Details)	Sep. 30, 2021 item
Office Properties Held For Sale [Member] | Suburban [Member] | Valuation Technique, Discounted Cash Flow [Member] | Measurement Assumptions, Discount Rates [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing Asset, Measurement Input	0.10
Office Properties Held For Sale [Member] | Suburban [Member] | Valuation Technique, Discounted Cash Flow [Member] | Measurement Assumptions, Market Rental Rates Per Square Foot [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing Asset, Measurement Input	34.50
Office Properties Held For Sale [Member] | Suburban [Member] | Valuation Technique, Discounted Cash Flow [Member] | Minimum [Member] | Measurement Assumptions, Exit Capitalization Rates [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing Asset, Measurement Input	0.085
Office Properties Held For Sale [Member] | Suburban [Member] | Valuation Technique, Discounted Cash Flow [Member] | Maximum [Member] | Measurement Assumptions, Exit Capitalization Rates [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing Asset, Measurement Input	0.0925
Office Properties Held For Sale [Member] | Waterfront [Member] | Valuation Technique, Discounted Cash Flow [Member] | Measurement Assumptions, Discount Rates [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing Asset, Measurement Input	0.08
Office Properties Held For Sale [Member] | Waterfront [Member] | Valuation Technique, Discounted Cash Flow [Member] | Minimum [Member] | Measurement Assumptions, Market Rates Per Square Foot [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing Asset, Measurement Input	48.00
Office Properties Held For Sale [Member] | Waterfront [Member] | Valuation Technique, Discounted Cash Flow [Member] | Maximum [Member] | Measurement Assumptions, Market Rates Per Square Foot [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing Asset, Measurement Input	51.00
Land Holdings Held For Sale [Member] | Suburban [Member] | Valuation Technique, Consensus Pricing Model [Member] | Measurement Assumptions, Market Rates Per Square Foot [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing Asset, Measurement Input	12.00
Land Holdings Held For Sale [Member] | Suburban [Member] | Valuation Technique, Consensus Pricing Model [Member] | Minimum [Member] | Measurement Assumptions, Market Rates Per Square Foot [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing Asset, Measurement Input	43,000
Land Holdings Held For Sale [Member] | Suburban [Member] | Valuation Technique, Consensus Pricing Model [Member] | Maximum [Member] | Measurement Assumptions, Market Rates Per Square Foot [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing Asset, Measurement Input	54,000
Land Holdings Held For Sale [Member] | Waterfront [Member] | Valuation Technique, Consensus Pricing Model [Member] | Minimum [Member] | Measurement Assumptions, Market Rates Per Square Foot [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing Asset, Measurement Input	60,000
Land Holdings Held For Sale [Member] | Waterfront [Member] | Valuation Technique, Consensus Pricing Model [Member] | Maximum [Member] | Measurement Assumptions, Market Rates Per Square Foot [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing Asset, Measurement Input	85,000