Stockholders' Equity and Equity Instruments (Tables)
 9 Months Ended
Sep. 30, 2012
Stockholders' Equity and Equity Instruments [Abstract]  
Range of Estimates and Calculated Fair Values of Options Granted in Period
To estimate the fair value of options on the grant date, the Company uses the Black-Scholes option valuation model.  Award recipients are grouped according to expected exercise behavior. Unless better information is available to estimate the expected term of the options, the estimate is based on historical exercise experience. The risk-free rate, using U.S. Treasury yield curves in effect at the time of grant, is selected based on the expected term of each group. The Company's historical stock price is used to estimate expected volatility.  The range of estimates and calculated fair values for options granted during 2012 is included in the table below. The weighted-average grant date fair value of these options was $22.99.
 
   
Range
 
Fair value of options granted
 $21.85 - $24.84 
Exercise price
 $71.69 - $76.81 
Expected term (years)
  3 - 6 
Expected volatility
  44.4% - 47.9%
Dividend yield
  2.5%
Risk-free rate of return
  0.7% - 1.1%
Stock-based Compensation Activity
During the nine months ended September 30, 2012, the Company reissued 44,137 shares of treasury stock related to the exercise of stock options, 42,439 shares related to the release of RSUs which vested and 859 shares related to a stock payment.  The Company recorded additional tax benefits of $0.9 million from its equity compensation awards as additional paid-in capital during the first nine months of 2012. During the nine months ended September 30, 2012 and 2011, the Company recorded $5.4 million and $4.8 million, respectively, of compensation expense in each period pursuant to its stock-based compensation plans.  No amounts have been capitalized. The following table summarizes stock-based compensation activity during the nine months ended September 30, 2012.
 
   
Stock Options
  
RSUs
  
PSUs(a)
 
   
 
  
Weighted-average
  
 
  
Weighted-average
  
 
  
Weighted-average
 
   
Number
  
exercise price
  
Number
  
fair value
  
Number
  
fair value
 
Outstanding at December 31, 2011
  520,530  $57.94   109,264  $73.35   25,398  $91.99 
Granted
  92,472   71.87   40,889   71.87   24,534   74.87 
Exercised (b)
  (44,137)  34.97   -   -   -   - 
Released(b)
  (289)  77.11   (42,439)  58.99   -   - 
Cancelled/Expired
  -   -   (102)  78.36   -   - 
Outstanding at September 30, 2012
  568,576  $61.98   107,612  $78.45   49,932  $83.58 
 
(a)
PSUs are initially included in the table at the 100% attainment level at their grant date and at that level represent one share per unit.  The number of shares that will be ultimately issued are based upon the PSUs earned.  The 2010 PSU grant has earned 103% of its target through the first two performance periods.  The 2011 PSU grant earned 0% in its first performance period.  PSUs may earn between 0% and 150% in each performance period.
(b)
Common stock issued for exercised options and RSUs released were reissued from treasury stock.
Other Comprehensive Income
The Company's comprehensive income is comprised of net earnings, amortization of the unrealized net pension costs, the change in the unrealized loss on natural gas cash flow hedges and foreign currency translation adjustments.  The components of and changes in accumulated other comprehensive income as of and for the nine months ended September 30, 2012 are as follows (in millions):
 
   
Balance
  
 
  
Balance
 
   
December 31,
  
2012
  
September 30,
 
   
2011
  
Change
  
2012
 
Unrealized gain (loss) on net pension obligations
 $(5.3) $0.6  $(4.7)
Unrealized gain (loss) on cash flow hedges
  (3.4)  2.4   (1.0)
Cumulative foreign currency translation adjustment
  49.5   23.0   72.5 
Accumulated other comprehensive income
 $40.8  $26.0  $66.8