Derivative Instruments and Hedging Activities (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($) instrument	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) instrument	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Derivative [Line Items]
Total return swap income	$ 2,977,000	$ 2,154,000	$ 7,749,000	$ 6,174,000
Multifamily Housing Mortgage Revenue Bonds
Derivative [Line Items]
Bond subject to interest rate caps	254,900,000		254,900,000
Total Return Swap, Callable
Derivative [Line Items]
Total return swap income	2,900,000
Designated as Hedging Instrument | Interest Rate Swap
Derivative [Line Items]
Derivative, notional amount	$ 175,000,000.0		$ 175,000,000.0
Interest rate	2.30%		2.30%
Aggregate carrying value of the interest rate swap contracts	$ (2,900,000)		$ (2,900,000)		$ 800,000
Aggregate carrying value of the interest rate swap contracts, asset	0		0		1,000,000.0
Aggregate carrying value of the interest rate swap contracts, liability	2,900,000		2,900,000		200,000
Not Designated as Hedging Instrument | Total Return Swap, Callable
Derivative [Line Items]
Derivative, notional amount	254,900,000		254,900,000
Derivative, fair value, net	$ 0		$ 0		$ 0
Not Designated as Hedging Instrument | Total Return Swap, Callable | Multifamily Housing Mortgage Revenue Bonds
Derivative [Line Items]
Number of derivative instruments | instrument	4		4