4. Debt Applicable Margin of Unsecured Term Loan (Details)	9 Months Ended
	Sep. 30, 2013
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.85%
Pricing Level 1 [Member] | Libor Rate Loans [Member] | Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.75%
Pricing Level 1 [Member] | Base Rate Loans [Member] | Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.75%
Pricing Level 2 [Member] | Libor Rate Loans [Member] | Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.90%
Pricing Level 2 [Member] | Base Rate Loans [Member] | Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.90%
Pricing Level 3 [Member] | Libor Rate Loans [Member] | Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.05%
Pricing Level 3 [Member] | Base Rate Loans [Member] | Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.05%
Pricing Level 4 [Member] | Libor Rate Loans [Member] | Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.20%
Pricing Level 4 [Member] | Base Rate Loans [Member] | Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.20%
Pricing Level 5 [Member] | Libor Rate Loans [Member] | Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.40%
Pricing Level 5 [Member] | Base Rate Loans [Member] | Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.40%
Maximum [Member] | Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	60.00%
Maximum [Member] | Pricing Level 1 [Member] | Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	35.00%
Maximum [Member] | Pricing Level 2 [Member] | Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	40.00%
Maximum [Member] | Pricing Level 3 [Member] | Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	45.00%
Maximum [Member] | Pricing Level 4 [Member] | Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	52.50%
Minimum [Member] | Pricing Level 2 [Member] | Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	35.00%
Minimum [Member] | Pricing Level 3 [Member] | Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	40.00%
Minimum [Member] | Pricing Level 4 [Member] | Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	45.00%
Minimum [Member] | Pricing Level 5 [Member] | Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	52.50%