title: xbrl us gaap contextRef standard?
body: <p>Please tell me this is standardized, or at least there is some way to decipher it.</p>
  
  <p>I'm looking at these 3 random 10-Qs and Ks from 2012Q4.</p>
  
  <ol>
  <li><a href="ftp://ftp.sec.gov/edgar/data/1001288/0001001288-12-000041.txt" rel="noreferrer">ftp://ftp.sec.gov/edgar/data/1001288/0001001288-12-000041.txt</a></li>
  <li><a href="ftp://ftp.sec.gov/edgar/data/1002037/0001193125-12-506687.txt" rel="noreferrer">ftp://ftp.sec.gov/edgar/data/1002037/0001193125-12-506687.txt</a></li>
  <li><a href="ftp://ftp.sec.gov/edgar/data/1002360/0001000096-12-000199.txt" rel="noreferrer">ftp://ftp.sec.gov/edgar/data/1002360/0001000096-12-000199.txt</a></li>
  </ol>
  
  <p>The line items are standardized; however, there are many of them per document.  For instance, one document will have a few <code>us-gaap:OperatingIncomeLoss</code>es, and the only way I can tell that they denote which period they are reporting is with <code>contextRef</code>.  That's where things get complicated.</p>
  
  <p>I see no discernible pattern.  Sometimes they're ascending then descending.  They all have their own date formats.  Some do multi-period grouping.  Some don't.</p>
  
  <p>I've tried to find a standard on this.  No go.</p>
  
  <p>Does anyone have any ideas?</p>
  
  <p>Many thanks!</p>