Consolidated Statement of Stockholders' Equity (Unaudited) - USD ($)
$ in Thousands
Total
Common Stock
Treasury Stock
Additional Paid-In Capital
Retained Earnings
Stockholders' equity at beginning of period at Dec. 31, 2017 $ 358,872 $ 3 $ (69,818) $ 337,445 $ 91,242
Shares at beginning of period (in shares) at Dec. 31, 2017   30,768,050 (3,526,870)    
Increase in stockholders' equity:          
Share compensation expense 2,350     2,350  
Exercise of stock options 1,239 $ 0   1,239  
Exercise of stock options (in shares)   123,442      
Common stock issued for vested restricted stock 0 $ 0   0  
Common stock issued for vested restricted stock (in shares)   195,853      
Common stock issued for vested performance shares 0 $ 0   0  
Common stock issued for vested performance shares (in shares)   26,567      
Common shares withheld and retired to satisfy employee tax withholding obligations upon vesting of restricted stock (2,222) $ 0   (2,222)  
Common shares withheld and retired to satisfy employee tax withholding obligations upon vesting of restricted stock (in shares)   (78,812)      
Net income 4,727       4,727
Stockholders' equity at end of period at Mar. 31, 2018 366,101 $ 3 $ (69,818) 338,811 97,105
Shares at end of period (in shares) at Mar. 31, 2018   31,035,100 (3,526,870)    
Stockholders' equity at beginning of period at Dec. 31, 2017 358,872 $ 3 $ (69,818) 337,445 91,242
Shares at beginning of period (in shares) at Dec. 31, 2017   30,768,050 (3,526,870)    
Increase in stockholders' equity:          
Net income 12,405        
Stockholders' equity at end of period at Jun. 30, 2018 378,218 $ 3 $ (69,818) 343,249 104,783
Shares at end of period (in shares) at Jun. 30, 2018   31,243,465 (3,526,870)    
Stockholders' equity at beginning of period at Mar. 31, 2018 366,101 $ 3 $ (69,818) 338,811 97,105
Shares at beginning of period (in shares) at Mar. 31, 2018   31,035,100 (3,526,870)    
Increase in stockholders' equity:          
Share compensation expense 2,212     2,212  
Exercise of stock options 2,322 $ 0   2,322  
Exercise of stock options (in shares)   201,900      
Common stock issued for vested restricted stock 0 $ 0   0  
Common stock issued for vested restricted stock (in shares)   9,870      
Common shares withheld and retired to satisfy employee tax withholding obligations upon vesting of restricted stock (96) $ 0   (96)  
Common shares withheld and retired to satisfy employee tax withholding obligations upon vesting of restricted stock (in shares)   (3,405)      
Net income 7,678       7,678
Stockholders' equity at end of period at Jun. 30, 2018 378,218 $ 3 $ (69,818) 343,249 104,783
Shares at end of period (in shares) at Jun. 30, 2018   31,243,465 (3,526,870)    
Stockholders' equity at beginning of period at Dec. 31, 2018 389,932 $ 3 $ (79,571) 348,397 121,102
Shares at beginning of period (in shares) at Dec. 31, 2018   31,345,220 (3,947,460)    
Increase in stockholders' equity:          
Share compensation expense 2,806     2,806  
Exercise of stock options 37 $ 0   37  
Exercise of stock options (in shares)   3,000      
Common stock issued for vested restricted stock 0 $ 0   0  
Common stock issued for vested restricted stock (in shares)   215,071      
Common stock issued for vested performance shares 0 $ 0   0  
Common stock issued for vested performance shares (in shares)   13,267      
Common shares withheld and retired to satisfy employee tax withholding obligations upon vesting of restricted stock (1,978) $ 0   (1,978)  
Common shares withheld and retired to satisfy employee tax withholding obligations upon vesting of restricted stock (in shares)   (81,936)      
Repurchase of convertible notes, net of deferred taxes 36     36  
Purchases of treasury stock (10,629)   $ (10,629)    
Purchase of treasury stock (in shares)     (452,350)    
Net income 3,497       3,497
Stockholders' equity at end of period at Mar. 31, 2019 383,700 $ 3 $ (90,199) 349,298 124,599
Shares at end of period (in shares) at Mar. 31, 2019   31,494,622 (4,399,810)    
Stockholders' equity at beginning of period at Dec. 31, 2018 389,932 $ 3 $ (79,571) 348,397 121,102
Shares at beginning of period (in shares) at Dec. 31, 2018   31,345,220 (3,947,460)    
Increase in stockholders' equity:          
Net income 8,564        
Stockholders' equity at end of period at Jun. 30, 2019 375,729 $ 3 $ (105,679) 351,739 129,666
Shares at end of period (in shares) at Jun. 30, 2019   31,498,159 (5,101,583)    
Stockholders' equity at beginning of period at Mar. 31, 2019 383,700 $ 3 $ (90,199) 349,298 124,599
Shares at beginning of period (in shares) at Mar. 31, 2019   31,494,622 (4,399,810)    
Increase in stockholders' equity:          
Share compensation expense 2,425     2,425  
Common stock issued for vested restricted stock 0 $ 0   0  
Common stock issued for vested restricted stock (in shares)   5,789      
Common shares withheld and retired to satisfy employee tax withholding obligations upon vesting of restricted stock (49) $ 0   (49)  
Common shares withheld and retired to satisfy employee tax withholding obligations upon vesting of restricted stock (in shares)   (2,252)      
Repurchase of convertible notes, net of deferred taxes 66     66  
Purchases of treasury stock (15,480)   $ (15,480)    
Purchase of treasury stock (in shares)     (701,773)    
Net income 5,067       5,067
Stockholders' equity at end of period at Jun. 30, 2019 $ 375,729 $ 3 $ (105,679) $ 351,739 $ 129,666
Shares at end of period (in shares) at Jun. 30, 2019   31,498,159 (5,101,583)