Credit Facilities and Mortgage Notes Payable (Unsecured Credit Facility Narrative) (Details) (USD $) In Millions, unless otherwise specified	5 Months Ended			9 Months Ended	1 Months Ended	5 Months Ended						2 Months Ended
	Sep. 30, 2014 Revolving Credit Facility [Member]	Sep. 30, 2014 Letter of Credit [Member]	Oct. 01, 2014 Subsequent Event [Member] Letter of Credit [Member]	Sep. 30, 2014 Unsecured Credit Facility [Member]	Jul. 31, 2014 Unsecured Credit Facility [Member] Term Loan [Member]	Sep. 30, 2014 Unsecured Credit Facility [Member] Term Loan [Member]	Sep. 30, 2014 Unsecured Credit Facility [Member] Revolving Credit Facility [Member]	Sep. 30, 2014 Unsecured Credit Facility [Member] Minimum [Member] Libor Rate [Member]	Sep. 30, 2014 Unsecured Credit Facility [Member] Minimum [Member] Base Rate [Member]	Sep. 30, 2014 Unsecured Credit Facility [Member] Maximum [Member] Libor Rate [Member]	Sep. 30, 2014 Unsecured Credit Facility [Member] Maximum [Member] Base Rate [Member]	Sep. 30, 2014 Senior Notes [Member]
Debt Instrument [Line Items]
Credit facility agreement date				May 01, 2013
Credit facility maximum borrowing capacity				$ 560		$ 150	$ 410
Unsecured credit facility term	4 years					5 years
Maximum the credit facility may be increased up until				600
Senior notes due												2022
Additional letter of credit outstanding		3.0	2.5
Leverage ratio								2.10%	1.10%	2.85%	1.85%
Line of credit facility weighted average interest rate outstanding percentage				2.26%
Repayment of term loan					$ 75
Interest rate												5.875%