Note 3 - Acquisitions - Allocation of Purchase Price Consideration (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2019	Oct. 01, 2019	Jan. 08, 2019	Dec. 31, 2018	May 01, 2017
Goodwill, Ending Balance	$ 429,597	$ 429,597	$ 429,597			$ 172,129
New Wave [Member]
Cash and cash equivalents							$ 12,220
Accounts receivable							15,027
Prepaid and other current assets							2,286
Property, plant and equipment							192,234
Intangible assets							476,300
Other noncurrent assets							1,184
Total Assets Acquired							699,251
Accounts payable and accrued liabilities							25,125
Deferred revenue							14,516
Deferred income taxes							6,644
Total Liabilities Assumed							46,285
Net assets acquired							652,966
Purchase price consideration							740,166
Goodwill, Ending Balance	87,200	87,200	87,200				$ 87,200
Clearwave [Member]
Cash and cash equivalents	1,913	1,913	1,913		$ 1,913
Accounts receivable	1,294	1,294	1,294		1,294
Prepaid and other current assets	311	311	311		311
Property, plant and equipment	120,472	120,472	120,472		120,472
Intangible assets	89,700	89,700	89,700		89,700
Other noncurrent assets	3,533	3,533	3,533		3,533
Total Assets Acquired	217,223	217,223	217,223		217,223
Accounts payable and accrued liabilities	2,128	2,128	2,128		2,128
Deferred revenue	4,322	4,322	4,322		4,322
Deferred income taxes	32,771	32,771	32,771		30,104
Total Liabilities Assumed	44,278	44,278	44,278		41,611
Net assets acquired	172,945	172,945	172,945		175,612
Purchase price consideration	358,830	358,830	358,830		358,830
Goodwill, Ending Balance	185,885	185,885	185,885		183,218
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Deferred Income Taxes		2,700	2,667
Other noncurrent liabilities	5,057	5,057	5,057		$ 5,057
Total Liabilities Assumed, adjustment			2,667
Net assets acquired, adjustment			(2,667)
Goodwill, Purchase Accounting Adjustments		2,700	2,667
Fidelity [Member]
Cash and cash equivalents	4,869	4,869	4,869	$ 4,869
Accounts receivable	3,691	3,691	3,691	3,691
Prepaid and other current assets	1,756	1,756	1,756	1,756
Property, plant and equipment	173,904	173,904	173,904	173,806
Intangible assets	288,000	288,000	288,000	288,000
Other noncurrent assets	1,895	1,895	1,895	481
Total Assets Acquired	474,115	474,115	474,115	472,603
Accounts payable and accrued liabilities	8,795	8,795	8,795	8,426
Deferred revenue	1,796	1,796	1,796	1,464
Total Liabilities Assumed	14,306	14,306	14,306	12,560
Net assets acquired	459,809	459,809	459,809	460,043
Purchase price consideration	531,392	531,392	531,392	529,349
Goodwill, Ending Balance	71,583	71,583	71,583	69,306
Other noncurrent liabilities	3,715	3,715	$ 3,715	$ 2,670
Total Liabilities Assumed, adjustment	1,746
Net assets acquired, adjustment	(234)
Goodwill, Purchase Accounting Adjustments	2,277	$ 2,300
Property, plant and equipment	98
Other noncurrent assets	1,414
Total Assets Acquired	1,512
Accounts payable and accrued liabilities	369
Deferred revenue, short-term portion, adjustment	332
Other noncurrent liabilities	1,045
Purchase price consideration	$ 2,043