Notes Payable and Unsecured Credit Facilities Weighted Average Debt Rates (Details)	Mar. 31, 2017
Effective Rate [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	1.90%
Effective Rate [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	4.60%
Effective Rate [Member] | Term Loan [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	2.40%
Contractual Rate [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	1.80%
Contractual Rate [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	4.10%
Contractual Rate [Member] | Term Loan [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	2.40%