4. Debt Applicable Margin of Unsecured Credit Facility (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.85%
Letters of Credit Outstanding, Amount	$ 0
Pricing Level 1 [Member] | Unsecured Credit Facility [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.85%
Pricing Level 1 [Member] | Unsecured Credit Facility [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.85%
Pricing Level 1 [Member] | Unsecured Credit Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	35.00%
Pricing Level 2 [Member] | Unsecured Credit Facility [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.00%
Pricing Level 2 [Member] | Unsecured Credit Facility [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.00%
Pricing Level 2 [Member] | Unsecured Credit Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	40.00%
Pricing Level 2 [Member] | Unsecured Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	35.00%
Pricing Level 3 [Member] | Unsecured Credit Facility [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.15%
Pricing Level 3 [Member] | Unsecured Credit Facility [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.15%
Pricing Level 3 [Member] | Unsecured Credit Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	45.00%
Pricing Level 3 [Member] | Unsecured Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	40.00%
Pricing Level 4 [Member] | Unsecured Credit Facility [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.30%
Pricing Level 4 [Member] | Unsecured Credit Facility [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.30%
Pricing Level 4 [Member] | Unsecured Credit Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	52.50%
Pricing Level 4 [Member] | Unsecured Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	45.00%
Pricing Level 5 [Member] | Unsecured Credit Facility [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.50%
Pricing Level 5 [Member] | Unsecured Credit Facility [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.50%
Pricing Level 5 [Member] | Unsecured Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	52.50%