Intangible Assets and Deferred Credits

Goodwill

The changes in the carrying value of goodwill for the year ended December 31, 2012 were as follows:



Balance as of December 31, 2011	$	2,035,390
Additions due to NextG Acquisition^(a)(b)	573,617
Additions due to WCP Acquisition^(a)(c)	54,824
Additions due to T-Mobile Acquisition^(a)(d)	428,019
Additions due to other acquisitions	28,113
Effect of exchange rate fluctuations	(6		)
Balance as of December 31, 2012	$	3,119,957


(a)	$573.6 million, $40.8 million and $363.6 million of the recorded amounts are not expected to be deductible for tax purposes in relation to the NextG Acquisition, WCP Acquisition and T-Mobile Acquisition, respectively.


(b)	The preliminary purchase price allocation for the NextG Acquisition resulted in the recognition of a substantial amount of goodwill at CCUSA relative to the purchase price based on the following:


•	the acquired and in-process DAS have low average tenancy, which the Company believes provides an opportunity to co-locate additional tenants on those systems;


•	the Company believes that the economics associated with DAS are similar to the economics associated with the Company's towers, whereby expected increases in revenues from additional tenants on existing DAS are expected to result in high incremental margins due to relatively fixed operating costs;


•	the Company believes the demand for tenants to co-locate on DAS will be driven by the continued growth trends in the wireless communication industry as wireless carriers continue to focus on improving network quality and expanding capacity;


•	the Company believes the acquired DAS are well-positioned to benefit from the anticipated growth in the wireless industry with their previously mentioned locations in the ten largest metropolitan statistical areas in the U.S.; and


•	other intangibles not qualified for separate recognition, including the assembled work force.

To a lesser extent, a portion of the goodwill recognized is the result of recording the tax impact of the NextG Acquisition. See also note 9.


(c)	The Company paid a purchase price for the WCP Acquisition that resulted in goodwill at CCUSA primarily because of the strategic opportunities related to the acquired portfolio.


(d)	The preliminary purchase price allocation for the T-Mobile Acquisition resulted in the recognition of goodwill at CCUSA primarily because of the anticipated growth opportunities in the tower portfolio.

Intangibles

The following is a summary of the Company's intangible assets.



	As of December 31, 2012							As of December 31, 2011
	Gross Carrying Value		Accumulated Amortization			Net Book Value		Gross Carrying Value		Accumulated Amortization			Net Book Value
Site rental contracts and customer relationships	$	3,566,207	$	(913,647	)	$	2,652,560	$	2,823,832	$	(748,850	)	$	2,074,982
Other intangible assets	354,208		(65,072		)	289,136		152,375		(49,175		)	103,200
Total	$	3,920,415	$	(978,719	)	$	2,941,696	$	2,976,207	$	(798,025	)	$	2,178,182

The components of the additions to intangible assets during the years ended December 31, 2012 are as follows:



	For Years Ended December 31,
	2012			2011
	Amount^(a)		Weighted-Average Amortization Period	Amount		Weighted-Average Amortization Period
			(In years)			(In years)
Site rental contracts and customer relationships	$	741,526	21.3	$	23,362	20.0
Other intangible assets	208,700		19.4	—		N/A
Total	$	950,226	20.9	$	23,362	20.0


(a)	Inclusive of $178.3 million related to below-market leases for land interests under acquired wireless infrastructure.

Amortization expense related to intangible assets is classified as follows on the Company's consolidated statement of operations and comprehensive income (loss):



	For Years Ended December 31,
Classification	2012		2011		2010
Depreciation, amortization and accretion	$	177,163	$	159,478	$	156,150
Site rental costs of operations	3,352		3,709		3,764
Total amortization expense	$	180,515	$	163,187	$	159,914

The estimated annual amortization expense related to intangible assets (inclusive of those recorded to "site rental costs of operations") for the years ended December 31, 2013 to 2017 is as follows:



	Years Ending December 31,
	2013		2014		2015		2016		2017
Estimated annual amortization	$	196,851	$	193,520	$	187,905	$	187,878	$	186,880

Deferred Credits

See note 2 for a further discussion of deferred credits related to above-market leases for land interests under the Company's towers recorded in connection with acquisitions. For the years ended December 31, 2012, 2011 and 2010, the Company recorded $3.4 million, $3.8 million and $4.4 million, respectively, as a decrease to "site rental costs of operations." The net book value of the above-market leases for land interests under the Company's towers was $58.2 million and $46.8 million as of December 31, 2012 and 2011, respectively.

The estimated annual amortization expense related to above-market leases for land interests under the Company's towers for the years ended December 31, 2013 to 2017 is as follows:



	Years Ending December 31,
	2013		2014		2015		2016		2017
Estimated annual amortization	$	4,361	$	4,337	$	4,322	$	4,280	$	4,250

During the twelve months ended December 31, 2012, the Company recorded deferred credits of $291.9 million related to below-market tenant leases as a result of the purchase price allocation for the NextG Acquisition (see note 3). Since the acquisition date, the Company has recognized a total of $20.8 million in site rental revenues related to the amortization of deferred credits. The net book value of the below-market tenants leases was $271.1 million as of December 31, 2012. The below-market tenant leases recorded during the twelve months ended December 31, 2012 have a weighted-average amortization period of 10 years.

The estimated annual amounts related to below-market tenant leases expected to be amortized into site rental revenues for the years ended December 31, 2013 to 2017 are as follows:



	Years Ending December 31,
	2013		2014		2015		2016		2017
Estimated annual amortization	$	30,443	$	30,263	$	28,937	$	28,512	$	25,628