Mortgage Loans Payable and Credit Facility (Summary of Derivative Financial Instruments Held) (Details) - Interest Rate Swap [Member] |
9 Months Ended | 12 Months Ended |
---|---|---|
Sep. 30, 2017
USD ($)
contract
|
Dec. 31, 2016
USD ($)
contract
|
|
Derivatives Fair Value [Line Items] | ||
Count | contract | 2 | 2 |
Fair value | $ | $ 1,392,000 | $ 2,321,000 |
Minimum [Member] | ||
Derivatives Fair Value [Line Items] | ||
Maturity dates | 2019 | 2019 |
Maximum [Member] | ||
Derivatives Fair Value [Line Items] | ||
Maturity dates | 2021 | 2021 |
Cash Flow Hedging, Count 3 [Member] | ||
Derivatives Fair Value [Line Items] | ||
Count | contract | 5 | 3 |
Fair value | $ | $ 3,614,000 | $ 3,074,000 |
Cash Flow Hedging, Count 3 [Member] | Minimum [Member] | ||
Derivatives Fair Value [Line Items] | ||
Maturity dates | 2020 | 2020 |
Cash Flow Hedging, Count 3 [Member] | Maximum [Member] | ||
Derivatives Fair Value [Line Items] | ||
Maturity dates | 2024 | 2023 |