Real Estate Intangibles

9 Months Ended

Sep. 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):



	September 30, 2019			December 31, 2018
Assets:
In place lease intangibles	$	1,486,255		$	1,410,725
Above market tenant leases	69,770			63,935
Below market ground leases ⁽¹⁾	—			64,513
Lease commissions	48,957			41,986
Gross historical cost	1,604,982			1,581,159
Accumulated amortization	(1,206,227		)	(1,197,336		)
Net book value	$	398,755		$	383,823

Weighted-average amortization period in years	9.5			16.0

Liabilities:
Below market tenant leases	$	94,581		$	81,676
Above market ground leases ⁽¹⁾	—			8,540
Gross historical cost	94,581			90,216
Accumulated amortization	(47,521		)	(44,266		)
Net book value	$	47,060		$	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 September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
Rental income related to (above)/below market tenant leases, net	$	291		$	(294	)	$	210		$	(978	)
Amortization related to in place lease intangibles and lease commissions	(48,414		)	(31,455		)	(101,837		)	(97,479		)

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



	Assets		Liabilities
2019	$	37,833	$	2,390
2020	103,599		8,868
2021	53,156		7,899
2022	36,057		7,163
2023	29,858		5,031
Thereafter	138,252		15,709
Total	$	398,755	$	47,060