Identified Intangible Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2015

Finite-Lived Intangible Assets [Line Items]

Schedule of Identified Intangible Assets and Intangible Liabilities [Table Text Block]

(Amounts in thousands)	Balance as of December 31,
	2015		2014
Identified intangible assets:
Gross amount	$	415,261	$	424,976
Accumulated amortization		(187,360)		(199,821)
Net	$	227,901	$	225,155
Identified intangible liabilities (included in deferred revenue):
Gross amount	$	643,488	$	657,976
Accumulated amortization		(325,340)		(329,775)
Net	$	318,148	$	328,201

Below Market Leases Net Of Above Market Leases [Member]

Finite-Lived Intangible Assets [Line Items]

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

(Amounts in thousands)
2016	$	52,359
2017		44,501
2018		43,028
2019		31,011
2020		23,320

Other Identified Intangible Assets [Member]

Finite-Lived Intangible Assets [Line Items]

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

(Amounts in thousands)
2016	$	29,349
2017		24,427
2018		20,063
2019		15,779
2020		12,345

Tenant Under Ground Leases [Member]

Finite-Lived Intangible Assets [Line Items]

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

(Amounts in thousands)
2016	$	1,832
2017		1,832
2018		1,832
2019		1,832
2020		1,832