Note 4 - Acquisition-related Items (Tables)	12 Months Ended
	Dec. 31, 2018
Notes Tables
Schedule of Acquisition Related Expenses [Table Text Block]	<div style="display: inline; font-family: times new roman; font-size: 10pt"><table cellpadding="0" cellspacing="0" style="border-collapse: collapse; margin: 0pt 0 0pt 30pt; min-; min-width: 700px;"> <tr style="vertical-align: bottom"> <td style="white-space: nowrap; font-size: 10pt"> </td> <td style="font-size: 10pt; font-weight: bold; padding-bottom: 1pt"> </td> <td colspan="2" style="white-space: nowrap; font-size: 10pt; font-weight: bold; text-align: right; border-bottom: Black 1pt solid">2018</td> <td style="white-space: nowrap; border-bottom: Black 1pt solid; font-size: 10pt; font-weight: bold; text-align: left"> </td> <td style="font-size: 10pt; padding-bottom: 1pt"> </td> <td colspan="2" style="white-space: nowrap; font-size: 10pt; text-align: right; border-bottom: Black 1pt solid">2017</td> <td style="white-space: nowrap; border-bottom: Black 1pt solid; font-size: 10pt; font-weight: bold; text-align: left"> </td> </tr> <tr style="vertical-align: bottom"> <td style="white-space: nowrap; font-size: 10pt"> </td> <td style="font-size: 10pt"> </td> <td colspan="2" style="white-space: nowrap; font-size: 10pt; text-align: right"> </td> <td style="font-size: 10pt"> </td> <td style="font-size: 10pt"> </td> <td colspan="2" style="white-space: nowrap; font-size: 10pt; text-align: right"> </td> <td style="font-size: 10pt"> </td> </tr> <tr style="vertical-align: bottom; background-color: rgb(204,238,255)"> <td style="width: 70%; font-size: 10pt; text-align: left">Transaction costs</td> <td style="width: 1%; font-size: 10pt; font-weight: bold"> </td> <td style="width: 1%; font-size: 10pt; font-weight: bold; text-align: left">$</td> <td style="width: 12%; font-size: 10pt; font-weight: bold; text-align: right"><div style="display: inline; font-style: italic; font-weight: inherit; font-style: normal;">11,747</div></td> <td style="white-space: nowrap; width: 1%; font-size: 10pt; font-weight: bold; text-align: left"> </td> <td style="width: 1%; font-size: 10pt"> </td> <td style="width: 1%; font-size: 10pt; text-align: left">$</td> <td style="width: 12%; font-size: 10pt; text-align: right"><div style="display: inline; font-style: italic; font-weight: inherit; font-style: normal;">6,247</div></td> <td style="white-space: nowrap; width: 1%; font-size: 10pt; text-align: left"> </td> </tr> <tr style="vertical-align: bottom; background-color: White"> <td style="font-size: 10pt; text-align: left">Contingent consideration fair value adjustments</td> <td style="font-size: 10pt; font-weight: bold"> </td> <td style="font-size: 10pt; font-weight: bold; text-align: left"> </td> <td style="font-size: 10pt; font-weight: bold; text-align: right"><div style="display: inline; font-style: italic; font-weight: inherit; font-style: normal;">1,675</div></td> <td style="white-space: nowrap; font-size: 10pt; font-weight: bold; text-align: left"> </td> <td style="font-size: 10pt"> </td> <td style="font-size: 10pt; text-align: left"> </td> <td style="font-size: 10pt; text-align: right"><div style="display: inline; font-style: italic; font-weight: inherit; font-style: normal;">1,054</div></td> <td style="white-space: nowrap; font-size: 10pt; text-align: left"> </td> </tr> <tr style="vertical-align: bottom; background-color: rgb(204,238,255)"> <td style="font-size: 10pt; text-align: left; padding-bottom: 1pt">Contingent consideration compensation expense</td> <td style="font-size: 10pt; font-weight: bold; padding-bottom: 1pt"> </td> <td style="border-bottom: Black 1pt solid; font-size: 10pt; font-weight: bold; text-align: left"> </td> <td style="border-bottom: Black 1pt solid; font-size: 10pt; font-weight: bold; text-align: right"><div style="display: inline; font-style: italic; font-weight: inherit; font-style: normal;">8,553</div></td> <td style="white-space: nowrap; border-bottom: Black 1pt solid; font-size: 10pt; font-weight: bold; text-align: left"> </td> <td style="font-size: 10pt; padding-bottom: 1pt"> </td> <td style="border-bottom: Black 1pt solid; font-size: 10pt; text-align: left"> </td> <td style="border-bottom: Black 1pt solid; font-size: 10pt; text-align: right"><div style="display: inline; font-style: italic; font-weight: inherit; font-style: normal;">7,626</div></td> <td style="white-space: nowrap; border-bottom: Black 1pt solid; font-size: 10pt; text-align: left"> </td> </tr> <tr style="vertical-align: bottom; background-color: White"> <td style="font-size: 10pt; padding-bottom: 1pt"> </td> <td style="font-size: 10pt; font-weight: bold; padding-bottom: 1pt"> </td> <td style="border-bottom: Black 1pt solid; font-size: 10pt; font-weight: bold; text-align: left">$</td> <td style="border-bottom: Black 1pt solid; font-size: 10pt; font-weight: bold; text-align: right"><div style="display: inline; font-style: italic; font-weight: inherit; font-style: normal;">21,975</div></td> <td style="white-space: nowrap; border-bottom: Black 1pt solid; font-size: 10pt; font-weight: bold; text-align: left"> </td> <td style="font-size: 10pt; padding-bottom: 1pt"> </td> <td style="border-bottom: Black 1pt solid; font-size: 10pt; text-align: left">$</td> <td style="border-bottom: Black 1pt solid; font-size: 10pt; text-align: right"><div style="display: inline; font-style: italic; font-weight: inherit; font-style: normal;">14,927</div></td> <td style="white-space: nowrap; border-bottom: Black 1pt solid; font-size: 10pt; text-align: left"> </td> </tr> </table></div>