Unsecured Revolving Credit Facility And Term Loans (Schedule Of Defined Leverage Ratio, Including Interest Rate, Alternate Base Rate Loans, And Facility Fee) (Details) - 2017 Credit Facility [Member]	6 Months Ended
	Jun. 30, 2020
Debt Instrument [Line Items]
Facility Fee Basis Points	0.25%
45% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Interest Rate - Applicable Basis Points Above LIBOR	1.25%
Facility Fee Basis Points	0.20%
45% Unsecured Term Loan Leverage Ratio [Member] | Maximum [Member]
Debt Instrument [Line Items]
Leverage ratio	45.00%
45% And 50% (Current ratio) Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Interest Rate - Applicable Basis Points Above LIBOR	1.30%
Facility Fee Basis Points	0.25%
45% And 50% (Current ratio) Unsecured Term Loan Leverage Ratio [Member] | Minimum [Member]
Debt Instrument [Line Items]
Leverage ratio	45.00%
45% And 50% (Current ratio) Unsecured Term Loan Leverage Ratio [Member] | Maximum [Member]
Debt Instrument [Line Items]
Leverage ratio	50.00%
50% And 55% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Interest Rate - Applicable Basis Points Above LIBOR	1.35%
Facility Fee Basis Points	0.30%
50% And 55% Unsecured Term Loan Leverage Ratio [Member] | Minimum [Member]
Debt Instrument [Line Items]
Leverage ratio	50.00%
50% And 55% Unsecured Term Loan Leverage Ratio [Member] | Maximum [Member]
Debt Instrument [Line Items]
Leverage ratio	55.00%
55% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Interest Rate - Applicable Basis Points Above LIBOR	1.60%
Facility Fee Basis Points	0.35%
55% Unsecured Term Loan Leverage Ratio [Member] | Minimum [Member]
Debt Instrument [Line Items]
Leverage ratio	55.00%
Base Rate [Member] | 45% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Interest Rate - Applicable Basis Points Above LIBOR	0.25%
Base Rate [Member] | 45% And 50% (Current ratio) Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Interest Rate - Applicable Basis Points Above LIBOR	0.30%
Base Rate [Member] | 50% And 55% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Interest Rate - Applicable Basis Points Above LIBOR	0.35%
Base Rate [Member] | 55% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Interest Rate - Applicable Basis Points Above LIBOR	0.60%