Note 7 - Fair Value Measurements (Details Textual) - USD ($) $ in Thousands		12 Months Ended
	Feb. 02, 2015	Dec. 31, 2018	Dec. 31, 2017	Jun. 14, 2017	Mar. 28, 2017	Mar. 17, 2017	Apr. 02, 2015
Deferred Capacity Revenue, Fair Value	$ 41,287
Service Obligation, Carrying Amount		$ 33,184	$ 35,255
Indefeasible Right of Use Assets, Fair Value Disclosure							$ 2,304
Indefeasible Right of Use Obligations, Fair Value Disclosure							$ 4,153
Impairment of Long-Lived Assets to be Disposed of		$ 0	$ 0
Minimum [Member]
Deferred Revenues, Amortization Period	10 years
Maximum [Member]
Deferred Revenues, Amortization Period	30 years
Interest Rate Swap [Member]
Derivative Final Notional Amount				$ 90,000
Derivative, Fixed Interest Rate				6.49425%
Interest Rate Swap [Member] | London Interbank Offered Rate (LIBOR) [Member]
Derivative, Basis Spread on Variable Rate				5.00%
6.25% Convertible Notes Due 2018 [Member]
Debt Instrument, Interest Rate, Stated Percentage			6.25%		6.25%	6.25%
6.25% Convertible Notes Due 2018 [Member] | Fair Value, Inputs, Level 2 [Member]
Debt and Capital Lease Obligations, Fair Value Disclosures			$ 10,026
Senior Credit Facilities and Other Long-Term Obligations [Member]
Debt and Capital Lease Obligations, Total		$ 172,494
The 2017 Senior Credit Facility [Member]
Debt Instrument Covenants, Minimum Borrowing		$ 90,000
Weighted Average Life of Senior Credit Facility		2 years