Real Estate Intangibles

6 Months Ended

Jun. 30, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

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, 2019			December 31, 2018
Assets:
In place lease intangibles	$	1,473,060		$	1,410,725
Above market tenant leases	69,656			63,935
Below market ground leases ⁽¹⁾	—			64,513
Lease commissions	46,422			41,986
Gross historical cost	1,589,138			1,581,159
Accumulated amortization	(1,163,936		)	(1,197,336		)
Net book value	$	425,202		$	383,823

Weighted-average amortization period in years	8.6			16.0

Liabilities:
Below market tenant leases	$	94,082		$	81,676
Above market ground leases ⁽¹⁾	—			8,540
Gross historical cost	94,082			90,216
Accumulated amortization	(45,147		)	(44,266		)
Net book value	$	48,935		$	45,950

Weighted-average amortization period in years	8.2			14.7

⁽¹⁾ Effective on January 1, 2019 with the adoption of ASC 842, above and below market ground lease intangibles are reported within the right of use assets, net line on the Consolidated Balance Sheet.

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



	Three Months Ended June 30,						Six Months Ended June 30,
	2019			2018			2019			2018
Rental income related to (above)/below market tenant leases, net	$	73		$	(333	)	$	(82	)	$	(684	)
Amortization related to in place lease intangibles and lease commissions	(28,518		)	(33,763		)	(53,423		)	(66,024		)

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



	Assets		Liabilities
2019	$	84,909	$	4,777
2020	101,374		8,835
2021	51,215		7,865
2022	34,495		7,130
2023	28,361		4,989
Thereafter	124,848		15,339
Total	$	425,202	$	48,935