Real Estate Intangibles

3 Months Ended

Mar. 31, 2013

Real Estate Intangibles [Abstract]

Real Estate Intangibles

4. Real Estate Intangibles

     The following is a summary of our real estate intangibles, excluding those classified as held for sale, as of the dates indicated (dollars in thousands):

		March 31, 2013		December 31, 2012
Assets:
	In place lease intangibles	$	678,368	$	541,729
	Above market tenant leases		56,024		56,086
	Below market ground leases		61,461		61,450
	Lease commissions		15,642		14,419
	Gross historical cost		811,495		673,684
	Accumulated amortization		(315,229)		(257,242)
	Net book value	$	496,266	$	416,442
	Weighted-average amortization period in years		13.7		16.4
Liabilities:
	Below market tenant leases	$	77,058	$	77,036
	Above market ground leases		9,490		9,490
	Gross historical cost		86,548		86,526
	Accumulated amortization		(29,652)		(27,753)
	Net book value	$	56,896	$	58,773
	Weighted-average amortization period in years		14.2		14.3

The following is a summary of real estate intangible amortization for the periods presented (in thousands):

	Three Months Ended
	March 31,
	2013		2012
Rental income related to above/below market tenant leases, net	$	148	$	552
Property operating expenses related to above/below market ground leases, net		(320)		(300)
Depreciation and amortization related to in place lease intangibles and lease commissions		(50,576)		(27,605)

     The future estimated aggregate amortization of intangible assets and liabilities is as follows for the periods presented (in thousands):

		Assets		Liabilities
2013	$	162,891	$	5,296
2014		91,723		6,608
2015		29,373		5,604
2016		23,039		5,220
2017		23,504		4,899
Thereafter		165,736		29,269
Totals	$	496,266	$	56,896