Subsequent Events (Details)	Oct. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	May. 31, 2014 USD ($)	Apr. 30, 2013 USD ($)
Forward Swap
Subsequent Event [Line Items]
Aggregate Notional Amount		$ 300,000,000	$ 225,000,000	$ 240,000,000
Subsequent Event | Forward Swap
Subsequent Event [Line Items]
Aggregate Notional Amount	$ 300,000,000
Interest rate cash flow hedge liability, fair value	13,369,000
Unsecured Debt | Subsequent Event
Subsequent Event [Line Items]
Principle amount of debt	$ 400,000,000
Stated interest rate	4.00%
Offering price, percentage	0.99759
Effective interest rate	4.029%