Debt Obligations, net (Narrative) (Details) $ in Thousands	1 Months Ended				12 Months Ended
	Nov. 30, 2021 USD ($)	May 31, 2021 USD ($)	Mar. 31, 2021 USD ($) item	Jul. 31, 2019 USD ($) loan	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Line of Credit Facility [Line Items]
Number of mortgages refinanced | loan				2
Loss on early extinguishment of debt				$ 2,000	$ 216	$ 0	$ 2,011
Secured Debt | Mortgages
Line of Credit Facility [Line Items]
Weighted average interest rate					3.99%
Unsecured Debt | 2.80% Senior Notes
Line of Credit Facility [Line Items]
Stated interest rate		2.80%			2.80%
Percent of par value at which the notes were issued		99.127%
Percentage of principal amount of debt at which debt can be redeemed		100.00%
Unencumbered assets to unsecured debt ration					1.25
Unsecured Debt | 2.85% Senior Notes
Line of Credit Facility [Line Items]
Aggregate principal amount	$ 350,000
Stated interest rate	2.85%				2.85%
Percent of par value at which the notes were issued	99.123%
Percentage of principal amount of debt at which debt can be redeemed	100.00%
2017 Revolver | Unsecured Debt
Line of Credit Facility [Line Items]
Maximum borrowing capacity			$ 1,000,000		$ 1,350,000
Number of extension options available | item			2
Debt extension term			12 months
Line of credit facility fee, percent			0.125%
Remaining borrowing capacity					$ 860,000
2017 Revolver | Unsecured Debt | 2.80% Senior Notes
Line of Credit Facility [Line Items]
Aggregate principal amount		$ 400,000
2017 Revolver | Unsecured Debt | LIBOR
Line of Credit Facility [Line Items]
Basis point spread on variable interest rate (percent)			1.00%		1.00%
Minimum | Unsecured Debt | 2.85% Senior Notes
Line of Credit Facility [Line Items]
Unencumbered assets to unsecured debt ration					1.25
Minimum | 2017 Revolver | Unsecured Debt
Line of Credit Facility [Line Items]
Unencumbered assets to unsecured debt ration					1.33
Debt instrument covenant multiple of minimum fixed charges on outstanding borrowings					1.15