Segments, Major Customers (Details)	3 Months Ended	6 Months Ended		12 Months Ended	3 Months Ended	6 Months Ended
	Jun. 30, 2013 Sales Revenue, Segment [Member] Customer Concentration Risk [Member] Customer	Jun. 30, 2013 Sales Revenue, Segment [Member] Customer Concentration Risk [Member] Customer	Jun. 30, 2013 United States [Member] Property, Plant and Equipment [Member] Geographic Concentration Risk [Member]	Dec. 31, 2012 United States [Member] Property, Plant and Equipment [Member] Geographic Concentration Risk [Member]	Jun. 30, 2012 Verizon [Member] Sales Revenue, Segment [Member] Customer Concentration Risk [Member]	Jun. 30, 2012 Verizon [Member] Sales Revenue, Segment [Member] Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk, number of major customers	0	0
Concentration risk, percentage			84.00%	83.00%	10.50%	11.30%