AMERICAN TOWER CORP /MA/ | 2013 | FY | 3

GOODWILL AND OTHER INTANGIBLE ASSETS
The changes in the carrying value of goodwill for the Company’s business segments are as follows (in thousands):
 
 
 
Rental and Management
 
Network
Development
Services
 
Total
 
 
Domestic
 
International
 
Balance as of January 1, 2013 (1)
 
$
2,320,571

 
$
520,072

 
$
2,000

 
$
2,842,643

Additions (2)
 
812,091

 
127,585

 
—

 
939,676

Effect of foreign currency translation
 
—

 
(52,418
)
 
—

 
(52,418
)
Balance as of December 31, 2013
 
$
3,132,662

 
$
595,239

 
$
2,000

 
$
3,729,901

(1) Balances have been revised to reflect purchase accounting measurement period adjustments.
(2)
Domestic and international rental and management segments include approximately $807.7 million and $67.3 million, respectively, of goodwill related to the Company’s acquisition of MIP Tower Holdings LLC (see note 6).

The Company’s other intangible assets subject to amortization consist of the following:
 
 
 
 
As of December 31, 2013
 
As of December 31, 2012 (1)
 
Estimated Useful
Lives
 
Gross
Carrying
Value
 
Accumulated
Amortization
 
Net Book
Value
 
Gross
Carrying
Value
 
Accumulated
Amortization
 
Net Book
Value
 
(years)
 
(in thousands)
Acquired network location (2)
Up to 20

 
$
2,365,474

 
$
(791,359
)
 
$
1,574,115

 
$
1,703,047

 
$
(721,135
)
 
$
981,912

Acquired customer-related intangibles
15-20

 
6,201,868

 
(1,170,239
)
 
5,031,629

 
3,133,603

 
(979,264
)
 
2,154,339

Acquired licenses and other intangibles
3-20

 
6,583

 
(2,297
)
 
4,286

 
26,079

 
(20,835
)
 
5,244

Economic Rights, TV Azteca
70

 
28,783

 
(14,229
)
 
14,554

 
28,954

 
(13,902
)
 
15,052

Total
 
 
$
8,602,708

 
$
(1,978,124
)
 
$
6,624,584

 
$
4,891,683

 
$
(1,735,136
)
 
$
3,156,547

Deferred financing costs, net (3)
N/A

 
 
 
 
 
76,875

 
 
 
 
 
49,538

Other intangible assets, net
 
 
 
 
 
 
$
6,701,459

 
 
 
 
 
$
3,206,085

(1)
December 31, 2012 balances have been revised to reflect purchase accounting measurement period adjustments.
(2)
Acquired network location intangibles are amortized over the shorter of the term of the corresponding ground lease taking into consideration lease renewal options and residual value or up to 20 years, as the Company considers these intangibles to be directly related to the tower assets.
(3)
Deferred financing costs are amortized over the term of the respective debt instruments to which they relate using the effective interest method. This amortization is included in interest expense, rather than in amortization expense.
The acquired network location intangible represents the value to the Company of the incremental revenue growth which could potentially be obtained from leasing the excess capacity on acquired communications sites. The acquired customer-related intangibles typically represent the value to the Company of customer contracts and relationships in place at the time of an acquisition, including assumptions regarding estimated renewals. During the year ended December 31, 2013, the Company retired $19.6 million of intangible assets related to non-competition agreements that had expired and were fully amortized.
The Company amortizes its acquired network intangibles and customer-related intangibles on a straight-line basis over the estimated useful lives. As of December 31, 2013, the remaining weighted average amortization period of the Company’s intangible assets, excluding the TV Azteca Economic Rights, is approximately 16 years. Amortization of intangible assets for the years ended December 31, 2013, 2012 and 2011 aggregated approximately $282.5 million, $207.3 million and $176.4 million (excluding amortization of deferred financing costs, which is included in interest expense), respectively. Based on current exchange rates, the Company expects to record amortization expense (excluding amortization of deferred financing costs) as follows over the next five years (in millions):
 
Year Ending December 31,
 
2014
$
426.1

2015
423.3

2016
420.5

2017
418.0

2018
415.8

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