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 September 30, 2018 and December 31, 2017.



	Balance as of
(Amounts in thousands)	September 30, 2018			December 31, 2017
Real Estate Intangibles:
Acquired in-place lease value:
Gross amount	$	1,452,050		$	1,473,515
Accumulated amortization	(748,087		)	(613,948		)
Net	$	703,963		$	859,567
Tenant relationship value:
Gross amount	$	1,969,111		$	1,978,277
Accumulated amortization	(261,618		)	(169,919		)
Net	$	1,707,493		$	1,808,358
Acquired above-market leases:
Gross amount	$	280,399		$	294,514
Accumulated amortization	(145,272		)	(110,139		)
Net	$	135,127		$	184,375
Acquired below-market leases:
Gross amount	$	443,457		$	469,119
Accumulated amortization	(235,255		)	(219,654		)
Net	$	208,202		$	249,465

Amortization of acquired below-market leases, net of acquired above-market leases, resulted in a (decrease)/increase in rental revenues of $(6.8) million and $0.7 million for the three months ended September 30, 2018 and 2017, respectively, and $(20.6) million and $4.7 million for the nine months ended September 30, 2018 and 2017, respectively. The expected average remaining lives for acquired below-market leases and acquired above-market leases is 8.3 years and 3.0 years, respectively, as of September 30, 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 October 1, 2018 is as follows:



(Amounts in thousands)
Remainder of 2018	$	(6,690	)
2019	(16,127		)
2020	(3,902		)
2021	899
2022	7,932
Thereafter	90,963
Total	$	73,075

Amortization of acquired in-place lease value (a component of depreciation and amortization expense) was $50.2 million and $20.1 million for the three months ended September 30, 2018 and 2017, respectively, and $162.3 million and $48.7 million for the nine months ended September 30, 2018 and 2017, respectively. The expected average amortization period for acquired in-place lease value is 6.2 years as of September 30, 2018. The weighted average remaining contractual life for acquired leases excluding renewals or extensions is 5.7 years as of September 30, 2018. Estimated annual amortization of acquired in-place lease value for each of the five succeeding years and thereafter, commencing October 1, 2018 is as follows:



(Amounts in thousands)
Remainder of 2018	$	47,782
2019	147,470
2020	111,611
2021	87,059
2022	65,179
Thereafter	244,862
Total	$	703,963

Amortization of tenant relationship value (a component of depreciation and amortization expense) was approximately $30.8 million and $19.9 million for the three months ended September 30, 2018 and 2017, respectively, and $92.8 million and $55.0 million for the nine months ended September 30, 2018 and 2017, respectively. As of September 30, 2018, the weighted average remaining contractual life for tenant relationship value was 14.5 years. Estimated annual amortization of tenant relationship value for each of the five succeeding years and thereafter, commencing October 1, 2018 is as follows:



(Amounts in thousands)
Remainder of 2018	$	30,808
2019	123,232
2020	123,232
2021	123,232
2022	123,232
Thereafter	1,183,757
Total	$	1,707,493