Notes Payable and Unsecured Credit Facilities (Tables)

12 Months Ended

Dec. 31, 2014

Debt Instrument [Line Items]

Schedule of Debt [Table Text Block]

	2014		2013
Notes payable:
Fixed rate mortgage loans	$	518,993	444,245
Variable rate mortgage loans (1)	29,839		37,100
Fixed rate unsecured loans	1,397,525		1,298,352
Total notes payable	1,946,357		1,779,697
Unsecured credit facilities:
Line	—		—
Term Loan	75,000		75,000
Total unsecured credit facilities	75,000		75,000
Total debt outstanding	$	2,021,357	1,854,697

Schedule of Line of Credit Facilities [Table Text Block]

As of December 31, 2014, the key terms of the Line and Term Loan are as follows (dollars in thousands):

	Total Capacity			Remaining Capacity			Maturity		Variable Interest Rate (6)	Fee
Line	$	800,000	(1)	$	794,096	(2)	9/4/2016	(3)	LIBOR plus 117.5 basis points	0.225%	(4)
Term Loan	165,000		(5)	90,000			6/27/2019		LIBOR plus 115 basis points	0.200%	(7)

Schedule of Maturities of Long-term Debt [Table Text Block]

As of December 31, 2014, scheduled principal payments and maturities on notes payable and unsecured credit facilities were as follows (in thousands):

Scheduled Principal Payments and Maturities by Year:	Scheduled Principal Payments		Mortgage Loan Maturities	Unsecured Maturities (1)		Total
2015	$	6,587	75,896	350,000		432,483
2016	6,135		41,442	—		47,577
2017	5,399		116,207	400,000		521,606
2018	4,452		57,358	—		61,810
2019	3,443		106,000	75,000		184,443
Beyond 5 Years	22,647		96,039	650,000		768,686
Unamortized debt premiums (discounts), net	—		7,227	(2,475	)	4,752
Total notes payable	$	48,663	500,169	1,472,525		2,021,357

Fixed Rate Mortgage Loans [Member]

Debt Instrument [Line Items]

Schedule of Long-term Debt Instruments [Table Text Block]

As of December 31, 2014, the key terms of the Company's fixed rate notes payable are as follows:

		Fixed Interest Rates
	Maturing Through	Minimum	Maximum	Weighted Average
Secured mortgage loans	2032	3.30%	8.40%	5.57%
Unsecured public debt	2024	3.75%	6.00%	5.17%

Variable Rate [Domain]

Debt Instrument [Line Items]

Schedule of Long-term Debt Instruments [Table Text Block]

As of December 31, 2014, the Company had one variable rate mortgage loan, which has an interest rate swap in place for the initial principal balance effectively fixing the interest rate through the maturity of the loan (as discussed in note 10), with key terms as follows ($ in thousands):

Balance		Maturity	Variable Interest Rate
$	29,839	10/16/2020	1 month LIBOR plus 150 basis points