Real Estate Intangibles

9 Months Ended

Sep. 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):


		September 30, 2014		December 31, 2013
Assets:
	In place lease intangibles	$	950,256	$	937,357
	Above market tenant leases		61,753		55,939
	Below market ground leases		61,593		59,165
	Lease commissions		18,765		18,293
	Gross historical cost		1,092,367		1,070,754
	Accumulated amortization		(749,847)		(571,008)
	Net book value	$	342,520	$	499,746

	Weighted-average amortization period in years		18.8		16.7

Liabilities:
	Below market tenant leases	$	79,555	$	76,381
	Above market ground leases		6,709		9,490
	Gross historical cost		86,264		85,871
	Accumulated amortization		(39,147)		(34,434)
	Net book value	$	47,117	$	51,437

	Weighted-average amortization period in years		13.2		14.3

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,
	2014		2013		2014		2013
Rental income related to above/below market tenant leases, net	$	179	$	235	$	423	$	596
Property operating expenses related to above/below market ground leases, net		(317)		(303)		(926)		(909)
Depreciation and amortization related to in place lease intangibles and lease commissions		(46,366)		(78,782)		(185,363)		(168,441)

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


		Assets		Liabilities
2014	$	40,573	$	3,328
2015		66,906		6,498
2016		31,821		7,264
2017		23,183		5,725
2018		20,761		5,380
Thereafter		159,276		18,922
Total	$	342,520	$	47,117