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Basis of Presentation and Significant Accounting Policies - Asset Retirement Obligations (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligations, beginning of year	$ 32,919	$ 31,663
Liabilities incurred	815	193
Acrrection expense	3,208	3,061	2,503
Decommissioned sites	(712)	(1,170)
Asset retirement obligations, end of year	36,230	32,919	31,663
STX Wireless [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Liabilities incurred	$ 0	$ (828)

The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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- Definition

Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability.

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