document.xsl

<?xml version="1.0" encoding="utf-8"?>

<xsl:stylesheet version="1.0"
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main">

<xsl:output method="text"
            encoding="utf-8"
            media-type="text/plain" />

<!-- ============================================================ -->

<xsl:template match="w:p">
  <xsl:if test="count(w:r/w:t) > 0">
    <xsl:apply-templates select="w:r/w:t" />

    <xsl:if test="count(following-sibling::node()/w:r/w:t) > 0">
      <xsl:text>&#13;&#10;</xsl:text>
      <xsl:text>&#13;&#10;</xsl:text>
    </xsl:if>
  </xsl:if>
</xsl:template>

<!-- ============================================================ -->

<xsl:template match="w:t">
  <xsl:value-of select="." disable-output-escaping="yes" />
</xsl:template>

</xsl:stylesheet>