Operating Segments and Concentrations of Credit Risk (Major Customers) (Details)	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Percentage of the consolidated revenues	74.00%	73.00%	74.00%
AT&T [Member]
Percentage of the consolidated revenues	23.00%	21.00%	20.00%
Sprint [Member]
Percentage of the consolidated revenues	21.00%	20.00%	22.00%
Verizon Wireless [Member]
Percentage of the consolidated revenues	19.00%	21.00%	19.00%
T-Mobile [Member]
Percentage of the consolidated revenues	11.00%	11.00%	13.00%