Acquired Intangible Assets and Liabilities

The following summarizes our acquired intangible assets (real estate intangibles, comprised of acquired in-place lease value and tenant relationship value along with acquired above-market lease value) and intangible liabilities (acquired below-market lease value) as of March 31, 2018 and December 31, 2017.



	Balance as of
(Amounts in thousands)	March 31, 2018			December 31, 2017
Real Estate Intangibles:
Acquired in-place lease value:
Gross amount	$	1,478,934		$	1,473,515
Accumulated amortization	(666,047		)	(613,948		)
Net	$	812,887		$	859,567
Tenant relationship value:
Gross amount	$	1,987,017		$	1,978,277
Accumulated amortization	(201,688		)	(169,919		)
Net	$	1,785,329		$	1,808,358
Acquired above-market leases:
Gross amount	$	285,963		$	294,514
Accumulated amortization	(120,395		)	(110,139		)
Net	$	165,568		$	184,375
Acquired below-market leases:
Gross amount	$	451,440		$	469,119
Accumulated amortization	(225,766		)	(219,654		)
Net	$	225,674		$	249,465

Amortization of acquired below-market leases, net of acquired above-market leases, resulted in a change in rental revenues of $(6.9) million and $2.0 million for the three months ended March 31, 2018 and 2017, respectively. The expected average remaining lives for acquired below-market leases and acquired above-market leases is 8.6 years and 3.5 years, respectively, as of March 31, 2018. Estimated annual amortization of acquired below-market leases, net of acquired above-market leases, for each of the five succeeding years and thereafter, commencing April 1, 2018 is as follows:



(Amounts in thousands)
Remainder of 2018	$	(31,936	)
2019	(15,513		)
2020	(3,145		)
2021	2,108
2022	9,118
Thereafter	99,474
Total	$	60,106

Amortization of acquired in-place lease value (a component of depreciation and amortization expense) was $57.0 million and $14.2 million for the three months ended March 31, 2018 and 2017, respectively. The expected average amortization period for acquired in-place lease value is 6.4 years as of March 31, 2018. The weighted average remaining contractual life for acquired leases excluding renewals or extensions is 6.1 years as of March 31, 2018. Estimated annual amortization of acquired in-place lease value for each of the five succeeding years and thereafter, commencing April 1, 2018 is as follows:



(Amounts in thousands)
Remainder of 2018	$	153,591
2019	148,067
2020	112,195
2021	87,579
2022	65,627
Thereafter	245,828
Total	$	812,887

Amortization of tenant relationship value (a component of depreciation and amortization expense) was approximately $31.0 million and $17.6 million for the three months ended March 31, 2018 and 2017, respectively. As of March 31, 2018, the weighted average remaining contractual life for tenant relationship value was 15.0 years. Estimated annual amortization of tenant relationship value for each of the five succeeding years and thereafter, commencing April 1, 2018 is as follows:



(Amounts in thousands)
Remainder of 2018	$	110,349
2019	142,181
2020	141,799
2021	141,799
2022	141,799
Thereafter	1,107,402
Total	$	1,785,329