Investments - Narrative (Details) - USD ($) $ in Thousands		12 Months Ended
	May 06, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Investments [Abstract]
Unrealized gains		$ 143
Unrealized losses			$ 141	$ 51
Dividends received from investments		110	134	$ 184
Business Acquisition [Line Items]
Increase in cost method investments		540	$ 388
Distributions from investments		2,900
Gain on equity method investment		$ 128
Ntelos Holding, Corp [Member]
Business Acquisition [Line Items]
Increase in cost method investments	$ 1,500