Identified Intangible Assets and Liabilities

3 Months Ended

Mar. 31, 2015

Identified Intangible Assets and Liabilities [Abstract]

Identified Intangible Assets and Intangible Liabilities

9. Identified Intangible Assets and Liabilities

The following summarizes our identified intangible assets (primarily acquired in-place and above-market leases) and liabilities (primarily acquired below-market leases) as of March 31, 2015 and December 31, 2014.

	Balance as of
	March 31,		December 31,
(Amounts in thousands)	2015		2014
Identified intangible assets:
Gross amount	$	429,909	$	424,976
Accumulated amortization		(200,330)		(199,821)
Net	$	229,579	$	225,155
Identified intangible liabilities (included in deferred revenue):
Gross amount	$	620,891	$	657,976
Accumulated amortization		(304,929)		(329,775)
Net	$	315,962	$	328,201

Amortization of acquired below-market leases, net of acquired above-market leases, resulted in anincrease to rental income of $12,450,000and$9,712,000for the three months ended March 31, 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, 2016 is as follows:

(Amounts in thousands)
2016	$	36,804
2017		34,829
2018		33,546
2019		23,514
2020		21,505

Amortization of all other identified intangible assets (a component of depreciation and amortization expense) was $6,185,000 and$8,891,000for the three months ended March 31, 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, 2016 is as follows:

(Amounts in thousands)
2016	$	22,523
2017		17,692
2018		13,373
2019		11,425
2020		10,651

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 $458,000for the three months ended March 31, 2015 and2014. Estimated annual amortization of these below-market leases, net of above-market leases for each of the five succeeding years commencing January 1, 2016 is as follows:

(Amounts in thousands)
2016	$	1,832
2017		1,832
2018		1,832
2019		1,832
2020		1,832