v3.8.0.1

Mortgages and Notes Payable - Summary of Mortgages and Notes Payable (Parenthetical) (Detail) | 12 Months Ended
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Dec. 31, 2017
Commercial Mortgage Rate |
Line Of Credit Facility [Line Items] |
Term of note | 5 years
Minimum |
Line Of Credit Facility [Line Items] |
Term of note | 59 months
Maximum |
Line Of Credit Facility [Line Items] |
Term of note | 239 months
M&T Bank | 1 Month LIBOR | New York State Energy Research and Development Authority Program |
Line Of Credit Facility [Line Items] |
Blended interest rate | 1.64%

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- Definition Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
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