Debt (Summary Of The Balances Outstanding And Interest Rate Spread) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Line of Credit	$ 48,000	$ 10,000
Outstanding balance, term loans	697,183	698,202
Deferred Loan Costs	(3,717)	(2,698)
$250 Million Senior Unsecured Revolving Line Of Credit ("Line of Credit") [Member]
Line of Credit	48,000	10,000
$225 Million Senior Unsecured Term Loan ("First Term Loan") [Member]
Outstanding balance, term loans	207,000	207,000
$300 Million Senior Unsecured Term Loan ("Second Term Loan") [Member]
Outstanding balance, term loans	300,000	300,000
$200 Million Senior Unsecured Term Loan ("Third Term Loan") [Member]
Outstanding balance, term loans	$ 193,900	$ 193,900
Minimum [Member] | $250 Million Senior Unsecured Revolving Line Of Credit ("Line of Credit") [Member]
Basis spread on variable rate (in hundredths)	1.50%
Minimum [Member] | $225 Million Senior Unsecured Term Loan ("First Term Loan") [Member]
Basis spread on variable rate (in hundredths)	1.45%
Minimum [Member] | $300 Million Senior Unsecured Term Loan ("Second Term Loan") [Member]
Basis spread on variable rate (in hundredths)	1.35%
Minimum [Member] | $200 Million Senior Unsecured Term Loan ("Third Term Loan") [Member]
Basis spread on variable rate (in hundredths)	1.45%
Maximum [Member] | $250 Million Senior Unsecured Revolving Line Of Credit ("Line of Credit") [Member]
Basis spread on variable rate (in hundredths)	2.25%
Maximum [Member] | $225 Million Senior Unsecured Term Loan ("First Term Loan") [Member]
Basis spread on variable rate (in hundredths)	2.20%
Maximum [Member] | $300 Million Senior Unsecured Term Loan ("Second Term Loan") [Member]
Basis spread on variable rate (in hundredths)	2.00%
Maximum [Member] | $200 Million Senior Unsecured Term Loan ("Third Term Loan") [Member]
Basis spread on variable rate (in hundredths)	2.20%