Consolidated Statements of Changes in Stockholders’ Equity - USD ($)
$ in Thousands
Common Stock
Class A
Common Stock
Class B
Common Stock
Pre-IPO
Treasury Stock
Class A
Treasury Stock
Class B
Treasury Stock
Pre-IPO
Additional Paid-In Capital
Accumulated Other Comprehensive Income (Loss)
Retained Deficit
Class A
Class B
Total
Balance at beginning of period at Dec. 31, 2016     $ 565     $ (16,245) $ 421,747 $ (537) $ (74,532)     $ 330,998
Balance at beginning of period (in shares) at Dec. 31, 2016     56,505,321     (1,719,529)            
Increase (Decrease) in Stockholders' Equity                        
Issuance of common stock, net of underwriter discount     $ 2       1,910         1,912
Issuance of common stock (in shares)     201,649                  
Repurchase of shares           $ (4,494)           (4,494)
Repurchase of shares           (332,660)            
Vesting of restricted share grants (in shares)     41,345                  
Equity awards modified to liabilities             (1,526)         (1,526)
Equity awards modified to liabilities (in shares)     (6,657)                  
Other comprehensive income (loss)               315       315
Stock-based compensation             5,862         5,862
Dividend                 (119,950)     (119,950)
Other                 (11)     (11)
Net income                 6,767     6,767
Balance at end of period at Jun. 30, 2017     $ 567     $ (20,739) 427,993 (222) (187,726)     219,873
Balance at end of period (in shares) at Jun. 30, 2017     56,741,658     (2,052,189)            
Balance at beginning of period at Dec. 31, 2017     $ 572     $ (20,899) 435,334 64 (183,888)     $ 231,183
Balance at beginning of period (in shares) at Dec. 31, 2017     57,182,730     (2,064,057)       0 0 55,118,673
Increase (Decrease) in Stockholders' Equity                        
Issuance of common stock, net of underwriter discount $ 128           156,421         $ 156,549
Issuance of common stock (in shares) 12,810,860                      
Class A common stock offering costs             (4,556)         (4,556)
Redesignation of common stock   $ 572 $ (572)   $ (20,899) $ 20,899            
Redesignation of common stock, (in shares)   57,184,766 (57,184,766)   (2,064,057) 2,064,057            
Share conversion - Class B to A $ 2 $ (2)                    
Share conversion - Class B to A (in shares) 160,650 (160,650)                    
Repurchase of shares       $ (720)               (720)
Repurchase of shares       (66,112)                
Vesting of restricted share grants (in shares)   30,992 2,036                  
Exercise of options             12         12
Exercise of options (in shares)   5,000                    
Fractional shares retired             (2)         (2)
Fractional shares retired (in shares)   (263)                    
Other comprehensive income (loss)               (17)       (17)
Stock-based compensation             7,470         7,470
Dividend                 (197)     (197)
Net income                 29,199     29,199
Balance at end of period at Jun. 30, 2018 $ 130 $ 570   $ (720) $ (20,899)   595,191 $ 47 (153,580)     $ 420,739
Balance at end of period (in shares) at Jun. 30, 2018 12,971,510 57,059,845   (66,112) (2,064,057)         12,905,398 54,995,788 0
Increase (Decrease) in Stockholders' Equity                        
Cumulative effect adjustment for adoption of ASU 2016-09             $ 512   $ 1,306     $ 1,818