Notes Payable and Unsecured Credit Facilities Weighted Average Debt Rates (Details)	Jun. 30, 2017
Effective Rate [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	2.00%
Effective Rate [Member] | Variable Rate Mortgage Loans [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	2.63%
Effective Rate [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	4.70%
Effective Rate [Member] | Term Loan [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	2.50%
Contractual Rate [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	1.90%
Contractual Rate [Member] | Variable Rate Mortgage Loans [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	2.43%
Contractual Rate [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	4.20%
Contractual Rate [Member] | Term Loan [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	2.40%