Secured and unsecured senior debt Repayment of secured note payable (Details)	Sep. 30, 2015
Debt Instrument [Line Items]
Effective rate (as a percent)	2.97%	[1]
Unsecured Bank Term Loan 2021 [Member]
Debt Instrument [Line Items]
Debt instrument number of six-month extension options	3
Effective rate (as a percent)	1.52%	[1]

[1] Represents the weighted-average interest rate as of the end of the period plus the impact of debt premiums/discounts and our interest rate swap agreements. The weighted-average interest rate excludes bank fees and amortization of loan fees.