XML 42 R22.htm IDEA: XBRL DOCUMENT  v2.3.0.11
Fair Value Measurements (Tables)
6 Months Ended
Jun. 30, 2011
Fair Value Measurements [Abstract]  
Fair value of plan assets
                                 
    Fair Value Measurements at June 30, 2011
            Quoted Prices in           Significant
            Active Markets for   Significant Other   Unobservable
            Identical Assets   Observable Inputs   Inputs
Assets   Total   (Level 1)   (Level 2)   (Level 3)
Money Market Funds
  $ 26.0     $ 26.0     $      
Natural Gas Derivatives
  $ 0.2     $     $ 0.2      
Oil Derivatives
  $     $     $