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Note 1 - Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Mar. 31, 2017	Sep. 30, 2017	Sep. 30, 2016
Net Cash Provided by (Used in) Operating Activities		$ 25,688	$ 28,364
Accounting Standards Update 2016-09 [Member]
Net Cash Provided by (Used in) Operating Activities			$ 51
Accounting Standards Update 2016-09 [Member] \| Change in Accounting for Excess Tax Benefits and Deficiencies [Member]
Cumulative Effect on Retained Earnings, Net of Tax	$ 1,441
Accounting Standards Update 2016-09 [Member] \| Change in Forfeiture Method [Member]
Cumulative Effect on Retained Earnings, Net of Tax	96
Cumulative Effect on Retained Earnings, before Tax	163
Cumulative Effect on Retained Earnings, Tax	$ 67
Noncontrolling Interest [Member] \| Quintillion Holdings, LLC [Member]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage		50.00%
ACS Cable Systems LLC and Quintillion Holdings, LLC Joint Venture [Member]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage		50.00%