Derivatives and Hedging Activities (Summary of Derivative Instruments) (Details)	Mar. 31, 2022 USD ($) derivative instrument	Dec. 31, 2021 USD ($) instrument
Derivative [Line Items]
Interest rate cap agreements excluded | derivative	3
Notional amount of interest rate caps excluded	$ 140,800,000
Interest rate caps | Fannie Mae Master Credit Facilities
Derivative [Line Items]
Number of Instruments | derivative	9
Notional Amount	$ 355,200,000
Interest rate cap	3.50%
Derivatives designated as hedging instruments: | Interest rate “pay-fixed” swaps
Derivative [Line Items]
Number of Instruments | instrument	9	9
Notional Amount	$ 578,500,000	$ 578,500,000
Derivatives not designated as hedging instruments: | Interest rate caps
Derivative [Line Items]
Number of Instruments | instrument	9	9
Notional Amount	$ 355,175,000	$ 355,175,000