Notes Payable and Unsecured Credit Facility (Narrative) (Details)	6 Months Ended
	Jun. 30, 2015 USD ($) loan	Jun. 30, 2014 USD ($)
Debt Instrument [Line Items]
Proceeds from notes payable	$ 64,305,000	$ 91,466,000
Proceeds from credit facility	160,000,000	20,000,000
Payments on credit facility	27,000,000	$ 97,000,000
Total unencumbered pool availability	352,000,000
Aggregate unencumbered pool availability	$ 144,000,000
Variable Rate, Subject To Interest Rate Swap [Member]
Debt Instrument [Line Items]
Number of notes payable | loan	6
Variable Rate, Subject To Interest Rate Swap [Member] | Note Payable One [Member]
Debt Instrument [Line Items]
Proceeds from notes payable	$ 37,000,000
Notes payable, variable rate basis	30-day London interbank offered rate
Notes payable, maturity date	Feb. 26, 2019
Notes payable, fixed interest rate through interest rate swap agreement	3.70%
Variable Rate, Subject To Interest Rate Swap [Member] | Note Payable One [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Notes payable, basis spread on variable rate	2.25%
Variable Rate [Member] | Note Payable Two [Member]
Debt Instrument [Line Items]
Proceeds from notes payable	$ 27,305,000
Notes payable, variable rate basis	30-day LIBOR rate
Notes payable, maturity date	Dec. 10, 2018
Variable Rate [Member] | Note Payable Two [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Notes payable, basis spread on variable rate	2.25%
Revolving Line Of Credit [Member]
Debt Instrument [Line Items]
Proceeds from credit facility	$ 160,000,000
Payments on credit facility	$ 27,000,000