Note 2 - Sale of Wireless Operations - Components of Gain on Sale of Assets (Details) - USD ($)			12 Months Ended
	Sep. 14, 2015	Feb. 02, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash					$ 44,688,000
Principal payment on 2010 Senior Credit Facility			$ 176,466,000	$ 13,421,000	333,961,000
Total consideration		$ 285,160,000			285,160,000
Equity investment in AWN					250,192,000
Assets and liabilities, net					5,121,000
Net change in deferred capacity revenue					(18,385,000)
Total carrying value of assets and liabilities sold					236,928,000
Gain on disposal of assets					48,232,000
2010 Senior Credit Facility [Member]
Principal payment on 2010 Senior Credit Facility	$ 81,526,000	$ 240,472,000			$ 240,472,000