Identified Intangible Assets and Liabilities

Identified intangible assets and liabilities associated with our property acquisitions are as follows (in thousands):



	December 31,
	2018			2017
Identified Intangible Assets:
Above-market leases (included in Other Assets, net)	$	38,181		$	44,231
Above-market leases - Accumulated Amortization	(19,617		)	(17,397		)
In place leases (included in Unamortized Lease Costs, net)	193,658			224,201
In place leases - Accumulated Amortization	(99,352		)	(96,202		)
	$	112,870		$	154,833
Identified Intangible Liabilities:
Below-market leases (included in Other Liabilities, net)	$	85,742		$	105,794
Below-market leases - Accumulated Amortization	(27,745		)	(28,072		)
Above-market assumed mortgages (included in Debt, net)	3,446			10,063
Above-market assumed mortgages - Accumulated Amortization	(1,660		)	(6,081		)
	$	59,783		$	81,704

These identified intangible assets and liabilities are amortized over the applicable lease terms or the remaining lives of the assumed mortgages, as applicable.

The net amortization of above-market and below-market leases increased rental revenues by $12.8 million, $3.7 million and $2.1 million in 2018, 2017 and 2016, respectively. The significant year over year change in rental revenues in 2018 to 2017 is primarily due to a write-off of a below-market lease intangible from the termination of a tenant's lease. The estimated net amortization of these intangible assets and liabilities will increase rental revenues for each of the next five years as follows (in thousands):



2019	$	2,668
2020	2,741
2021	2,712
2022	2,560
2023	2,529

The amortization of the in place lease intangible assets recorded in depreciation and amortization, was $29.8 million, $21.0 million and $18.0 million in 2018, 2017 and 2016, respectively. The significant year over year change in depreciation and amortization from 2018 to 2017 is primarily due to the write-off of in-place lease intangibles from the termination of tenant leases. The estimated amortization of these intangible assets will increase depreciation and amortization for each of the next five years as follows (in thousands):



2019	$	13,539
2020	12,564
2021	10,501
2022	8,472
2023	7,285

The net amortization of above-market assumed mortgages decreased net interest expense by $.7 million, $1.1 million and $1.0 million in 2018, 2017 and 2016, respectively. The estimated net amortization of these intangible liabilities will decrease net interest expense for each of the next five years as follows (in thousands):



2019	$	327
2020	327
2021	287
2022	141
2023	136