Real Estate Intangibles (Tables)

12 Months Ended

Dec. 31, 2017

Real Estate Intangibles (Tables) [Abstract]

Summary of real estate intangibles excluding those classified as held for sale

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):

		December 31, 2017		December 31, 2016
Assets:
	In place lease intangibles	$	1,352,139	$	1,252,143
	Above market tenant leases		58,443		61,700
	Below market ground leases		58,784		61,628
	Lease commissions		33,105		27,413
	Gross historical cost		1,502,471		1,402,884
	Accumulated amortization		(1,125,437)		(966,714)
	Net book value	$	377,034	$	436,170
	Weighted-average amortization period in years		15.1		13.7
Liabilities:
	Below market tenant leases	$	60,430	$	89,468
	Above market ground leases		8,540		8,107
	Gross historical cost		68,970		97,575
	Accumulated amortization		(39,629)		(52,134)
	Net book value	$	29,341	$	45,441
	Weighted-average amortization period in years		20.1		15.2

Schedule of Real Estate Intangible Amortization

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

	Year Ended December 31,
	2017		2016		2015
Rental income related to above/below market tenant leases, net	$	875	$	919	$	(2,746)
Property operating expenses related to above/below market ground leases, net		(1,231)		(1,241)		(1,272)
Depreciation and amortization related to in place lease intangibles and lease commissions		(145,132)		(132,141)		(115,855)

Schedule Of Future Intangible Amortization

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

		Assets		Liabilities
2018	$	111,339	$	3,765
2019		55,336		3,306
2020		34,402		2,809
2021		20,419		2,321
2022		17,213		1,856
Thereafter		138,325		15,284
Totals	$	377,034	$	29,341