Real Estate Intangibles

3 Months Ended

Sep. 30, 2012

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):

		September 30, 2012		December 31, 2011
Assets:
	In place lease intangibles	$	447,833	$	332,645
	Above market tenant leases		52,210		35,973
	Below market ground leases		60,771		51,316
	Lease commissions		11,951		8,265
	Gross historical cost		572,765		428,199
	Accumulated amortization		(230,217)		(148,380)
	Net book value	$	342,548	$	279,819
	Weighted-average amortization period in years		19.6		17.0
Liabilities:
	Below market tenant leases	$	72,442	$	67,284
	Above market ground leases		8,955		5,020
	Gross historical cost		81,397		72,304
	Accumulated amortization		(26,010)		(21,387)
	Net book value	$	55,387	$	50,917
	Weighted-average amortization period in years		14.5		12.3

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

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2012		2011		2012		2011
Rental income related to above/below market tenant leases, net	$	(972)	$	1,118	$	452	$	2,439
Property operating expenses related to above/below market ground leases, net		(555)		(315)		(1,219)		(851)
Depreciation and amortization related to in place lease intangibles and lease commissions		(22,271)		(28,263)		(78,114)		(69,804)

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

		Assets		Liabilities
2012	$	51,651	$	1,742
2013		38,021		6,534
2014		32,294		6,010
2015		22,877		5,014
2016		24,184		4,668
Thereafter		173,521		31,419
Totals	$	342,548	$	55,387