Derivative Instruments and Hedging Activities (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Derivative [Line Items]
Cash flow hedge ineffectiveness	$ 0	$ 0
Total return swap income	2,584,000	$ 3,123,000
Multifamily Housing Mortgage Revenue Bonds [Member]
Derivative [Line Items]
Bond subject to interest rate caps	257,300,000
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, notional amount	$ 200,000,000
Interest rate (in hundredths)	2.30%
Aggregate carrying value of the interest rate swap contracts, asset	$ 4,700,000		$ 4,400,000
Designated as Hedging Instrument [Member] | Interest Rate Cap [Member]
Derivative [Line Items]
Aggregate carrying value of the interest rate swap contracts, liability	0		0
Not Designated as Hedging Instrument [Member] | Total Return Swap [Member]
Derivative [Line Items]
Derivative, notional amount	20,700,000
Derivative, fair value, net	0		$ 0
Not Designated as Hedging Instrument [Member] | Total Return Swap, Callable [Member]
Derivative [Line Items]
Derivative, notional amount	$ 257,300,000