| Summary of changes in shareholders' equity | 
        
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   | 
Three Months Ended March 31, 2014  | 
 
   | 
(In thousands)  | 
 
   | 
 Number of 
Shares 
 | 
   | 
 Common 
Stock 
 | 
   | 
 Additional 
Paid-In 
Capital 
 | 
   | 
 Retained 
Earnings 
 | 
   | 
Total  | 
 
Balance at December 31, 2013  | 
36,244  | 
 
  | 
   | 
$  | 
362  | 
 
  | 
   | 
$  | 
412,961  | 
 
  | 
   | 
$  | 
428,069  | 
 
  | 
   | 
$  | 
841,392  | 
 
  | 
 
Net earnings  | 
—  | 
 
  | 
   | 
—  | 
 
  | 
   | 
—  | 
 
  | 
   | 
25,377  | 
 
  | 
   | 
25,377  | 
 
  | 
 
Exercise/vesting of equity awards  | 
340  | 
 
  | 
   | 
4  | 
 
  | 
   | 
703  | 
 
  | 
   | 
—  | 
 
  | 
   | 
707  | 
 
  | 
 
Excess income tax benefit from stock-based awards  | 
—  | 
 
  | 
   | 
—  | 
 
  | 
   | 
2,275  | 
 
  | 
   | 
—  | 
 
  | 
   | 
2,275  | 
 
  | 
 
Equity award compensation expense  | 
—  | 
 
  | 
   | 
—  | 
 
  | 
   | 
2,411  | 
 
  | 
   | 
—  | 
 
  | 
   | 
2,411  | 
 
  | 
 
Issuance of stock (1)  | 
2,530  | 
 
  | 
   | 
25  | 
 
  | 
   | 
110,407  | 
 
  | 
   | 
—  | 
 
  | 
   | 
110,432  | 
 
  | 
 
Balance at March 31, 2014  | 
39,114  | 
 
  | 
   | 
$  | 
391  | 
 
  | 
   | 
$  | 
528,757  | 
 
  | 
   | 
$  | 
453,446  | 
 
  | 
   | 
$  | 
982,594  | 
 
  | 
 
  
 
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   | 
Three Months Ended March 31, 2013  | 
 
   | 
(In thousands)  | 
 
   | 
 Number of 
Shares 
 | 
   | 
 Common 
Stock 
 | 
   | 
 Additional 
Paid-In 
Capital 
 | 
   | 
 Retained 
Earnings 
 | 
   | 
Total  | 
 
Balance at December 31, 2012  | 
35,613  | 
 
  | 
   | 
$  | 
356  | 
 
  | 
   | 
$  | 
390,249  | 
 
  | 
   | 
$  | 
303,605  | 
 
  | 
   | 
$  | 
694,210  | 
 
  | 
 
Net earnings  | 
—  | 
 
  | 
   | 
—  | 
 
  | 
   | 
—  | 
 
  | 
   | 
12,041  | 
 
  | 
   | 
12,041  | 
 
  | 
 
Exercise/vesting of equity awards  | 
397  | 
 
  | 
   | 
4  | 
 
  | 
   | 
3,074  | 
 
  | 
   | 
—  | 
 
  | 
   | 
3,078  | 
 
  | 
 
Excess income tax benefit from stock-based awards  | 
—  | 
 
  | 
   | 
—  | 
 
  | 
   | 
464  | 
 
  | 
   | 
—  | 
 
  | 
   | 
464  | 
 
  | 
 
Equity award compensation expense  | 
—  | 
 
  | 
   | 
—  | 
 
  | 
   | 
1,844  | 
 
  | 
   | 
—  | 
 
  | 
   | 
1,844  | 
 
  | 
 
Balance at March 31, 2013  | 
36,010  | 
 
  | 
   | 
$  | 
360  | 
 
  | 
   | 
$  | 
395,631  | 
 
  | 
   | 
$  | 
315,646  | 
 
  | 
   | 
$  | 
711,637  | 
 
  | 
 
  
 
 
(1)  In January 2014, we issued 2,530,000 shares of common stock in a secondary public offering, par value $0.01 per share, at a price of $45.75 per share.
 
 
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