Identified Intangible Assets and Liabilities

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



	December 31,
	2017			2016
Identified Intangible Assets:
Above-market leases (included in Other Assets, net)	$	44,231		$	44,595
Above-market leases - Accumulated Amortization	(17,397		)	(13,579		)
Below-market assumed mortgages (included in Debt, net)	—			1,671
Below-market assumed mortgages - Accumulated Amortization	—			(1,564		)
In place leases (included in Unamortized Lease Costs, net)	224,201			232,528
In place leases - Accumulated Amortization	(96,202		)	(82,571		)
	$	154,833		$	181,080
Identified Intangible Liabilities:
Below-market leases (included in Other Liabilities, net)	$	105,794		$	110,878
Below-market leases - Accumulated Amortization	(28,072		)	(23,109		)
Above-market assumed mortgages (included in Debt, net)	10,063			10,375
Above-market assumed mortgages - Accumulated Amortization	(6,081		)	(5,186		)
	$	81,704		$	92,958

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 (decreased) rental revenues by $3.7 million, $2.1 million and $(.5) million in 2017, 2016 and 2015, respectively. The significant year over year change in rental revenues in 2016 to 2015 is primarily due to acquisitions during 2016. 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):



2018	$	2,789
2019	3,161
2020	3,234
2021	3,186
2022	3,007

The amortization of the in place lease intangible assets recorded in depreciation and amortization, was $21.0 million, $18.0 million and $12.3 million in 2017, 2016 and 2015, respectively. The significant year over year change in depreciation and amortization from 2016 to 2015 is primarily due to acquisitions during 2016. The estimated amortization of these intangible assets will increase depreciation and amortization for each of the next five years as follows (in thousands):



2018	$	16,617
2019	14,638
2020	13,663
2021	11,573
2022	9,516

The net amortization of above-market and below-market assumed mortgages decreased net interest expense by $1.1 million, $1.0 million and $.7 million in 2017, 2016 and 2015, respectively. The estimated net amortization of these intangible assets and liabilities will decrease net interest expense for each of the next five years as follows (in thousands):



2018	$	1,207
2019	1,207
2020	436
2021	287
2022	141