Identified Intangible Assets and Liabilities

12 Months Ended

Dec. 31, 2016

Identified Intangible Assets and Liabilities [Abstract]

Identified Intangible Assets and Liabilities

7. Identified Intangible Assets and Liabilities

The following summarizes our identified intangible assets (primarily acquired above-market leases) and liabilities (primarily acquired below-market leases) as of December 31,2016 and2015.

(Amounts in thousands)	Balance as of December 31,
	2016		2015
Identified intangible assets:
Gross amount	$	400,061	$	415,261
Accumulated amortization		(207,330)		(187,360)
Net	$	192,731	$	227,901
Identified intangible liabilities (included in deferred revenue):
Gross amount	$	586,969	$	643,488
Accumulated amortization		(323,183)		(325,340)
Net	$	263,786	$	318,148

Amortization of acquired below-market leases, net of acquired above-market leases, resulted in an increase to rental income of $53,202,000, $78,749,000 and $37,516,000 for the years ended December 31, 2016, 2015 and 2014, 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	$	45,576
2018		44,346
2019		32,168
2020		23,343
2021		18,159

Amortization of all other identified intangible assets (a component of depreciation and amortization expense) was $29,543,000, $36,659,000 and $28,275,000 for the years ended December 31,2016, 2015 and 2014, 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	$	24,456
2018		20,201
2019		15,863
2020		12,394
2021		11,177

We are a tenant under ground leases at certain properties. Amortization of these acquired below-market leases, net of above-market leases, resulted in an increase to rent expense of $1,832,000, $1,832,000, and $1,832,000 for the years ended December 31,2016, 2015 and 2014. 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