Identified Intangible Assets and Liabilities

3 Months Ended

Mar. 31, 2016

Identified Intangible Assets and Liabilities [Abstract]

Identified Intangible Assets and Liabilities

8. Identified Intangible Assets and Liabilities

The following summarizes our identified intangible assets (primarily above-market leases) and liabilities (primarily acquired below-market leases) as of March 31, 2016 and December 31, 2015.

(Amounts in thousands)	Balance as of
	March 31, 2016		December 31, 2015
Identified intangible assets:
Gross amount	$	406,482	$	415,261
Accumulated amortization		(188,094)		(187,360)
Net	$	218,388	$	227,901
Identified intangible liabilities (included in deferred revenue):
Gross amount	$	607,241	$	643,488
Accumulated amortization		(307,858)		(325,340)
Net	$	299,383	$	318,148

Amortization of acquired below-market leases, net of acquired above-market leases, resulted in anincrease to rental income of $17,507,000and $12,450,000 for the three months ended March 31, 2016 and 2015, respectively. Estimated annual amortization of acquired below-market leases, net of acquired above-market leases, for each of the five succeeding years commencing January 1, 2017 is as follows:

(Amounts in thousands)
2017	$	44,463
2018		42,991
2019		30,973
2020		23,320
2021		18,263

Amortization of all other identified intangible assets (a component of depreciation and amortization expense) was $7,793,000 and $6,185,000for the three months ended March 31, 2016 and 2015, respectively. Estimated annual amortization of all other identified intangible assets including acquired in-place leases, customer relationships, and third party contracts for each of the five succeeding years commencing January 1, 2017 is as follows:

(Amounts in thousands)
2017	$	24,427
2018		20,063
2019		15,779
2020		12,345
2021		10,957

We are a tenant under ground leases for certain properties. Amortization of these acquired below-market leases, net of above-market leases, resulted in anincrease to rent expense of $458,000and $458,000 for the three months ended March 31, 2016 and2015, respectively. Estimated annual amortization of these below-market leases, net of above-market leases, for each of the five succeeding years commencing January 1, 2017 is as follows:

(Amounts in thousands)
2017	$	1,832
2018		1,832
2019		1,832
2020		1,832
2021		1,832