Intangible Assets, Net

3 Months Ended

Mar. 31, 2012

Intangible Assets, Net [Abstract]

Intangible Assets, Net

5. INTANGIBLE ASSETS, NET

The following table provides the gross and net carrying amounts for each major class of intangible assets:

	As of March 31, 2012							As of December 31, 2011
	Gross carrying amount		Accumulated amortization			Net book value		Gross carrying amount		Accumulated amortization			Net book value
	(in thousands)
Current contract intangibles	$	1,415,820	$	(356,843	)	$	1,058,977	$	1,391,001	$	(333,522	)	$	1,057,479
Network location intangibles		788,759		(203,302	)		585,457		772,467		(190,162	)		582,305
Intangible assets, net	$	2,204,579	$	(560,145	)	$	1,644,434	$	2,163,468	$	(523,684	)	$	1,639,784

All intangible assets noted above are included in our site leasing segment. The Company amortizes its intangible assets using the straight-line method over fifteen years. Amortization expense relating to the intangible assets above was $36.4 million and $32.0 million for the three months ended March 31, 2012 and 2011, respectively. These amounts are subject to changes in estimates until the preliminary allocation of the purchase price is finalized for all acquisitions.