Real Estate Intangibles

6 Months Ended

Jun. 30, 2014

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):


		June 30, 2014		December 31, 2013
Assets:
	In place lease intangibles	$	947,616	$	937,357
	Above market tenant leases		58,735		55,939
	Below market ground leases		60,088		59,165
	Lease commissions		18,264		18,293
	Gross historical cost		1,084,703		1,070,754
	Accumulated amortization		(713,334)		(571,008)
	Net book value	$	371,369	$	499,746

	Weighted-average amortization period in years		17.9		16.7

Liabilities:
	Below market tenant leases	$	78,723	$	76,381
	Above market ground leases		6,646		9,490
	Gross historical cost		85,369		85,871
	Accumulated amortization		(37,425)		(34,434)
	Net book value	$	47,944	$	51,437

	Weighted-average amortization period in years		13.1		14.3

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


	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2014		2013		2014		2013
Rental income related to above/below market tenant leases, net	$	290	$	213	$	245	$	361
Property operating expenses related to above/below market ground leases, net		(299)		(303)		(610)		(606)
Depreciation and amortization related to in place lease intangibles and lease commissions		(59,603)		(39,083)		(138,996)		(89,659)

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


		Assets		Liabilities
2014	$	77,024	$	3,421
2015		64,525		5,994
2016		30,515		5,580
2017		22,266		5,115
2018		19,317		4,729
Thereafter		157,722		23,105
Totals	$	371,369	$	47,944