Net Property and Equipment (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Cash payment	$ 19,700	$ 0	$ 0
Fair Market Value of IRU Capacity	14,000
Other Income (Expense) [Member]
Property, Plant and Equipment [Line Items]
Gain from adjustment to fair value	$ 3,100