Note 7 - Segment Reporting (Details Textual) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Number of Reportable Segments	2
Gross Profit, Total	$ 162,175	$ 141,927
Geographic Concentration Risk [Member] \| Revenue Benchmark [Member] \| UNITED STATES
Concentration Risk, Percentage	72.00%	71.00%
Geographic Concentration Risk [Member] \| Net Assets, Geographic Area [Member] \| UNITED STATES
Concentration Risk, Percentage	80.00%		80.00%
Accounting Standards Update 2014-09 [Member] \| Restatement Adjustment [Member]
Revenue from Contract with Customer, Including Assessed Tax		$ 2,457
Gross Profit, Total		$ 1,938

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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