Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Summary of Restricted Stock Activity (Details)

v3.10.0.1
Stockholders' Equity - Summary of Restricted Stock Activity (Details) - $ / shares
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Time based restricted stock units    
Class Of Stock [Line Items]    
Unvested restricted stock units/ awards outstanding, Beginning balance 42,028  
Granted 31,877 42,028
Vested (13,742)  
Forfeited/canceled (1,574)  
Unvested restricted stock units/ awards outstanding, Ending balance 58,589 42,028
Performance and time based restricted stock units    
Class Of Stock [Line Items]    
Unvested restricted stock units/ awards outstanding, Beginning balance 13,109  
Granted   13,109
Vested (4,370)  
Unvested restricted stock units/ awards outstanding, Ending balance 8,739 13,109
Restricted stock units    
Class Of Stock [Line Items]    
Unvested restricted stock units/ awards outstanding, Beginning balance 55,137  
Granted 31,877 55,137
Vested (18,112)  
Forfeited/canceled (1,574)  
Unvested restricted stock units/ awards outstanding, Ending balance 67,328 55,137
Unvested and expected to vest restricted stock units/awards outstanding 62,504 48,589
Weighted-average grant date fair value per share, Unvested restricted stock units/ awards outstanding, Beginning balance $ 90.05  
Weighted-average grant date fair value per share, Granted 143.50 $ 90.05
Weighted-average grant date fair value per share, Vested 89.35  
Weighted-average grant date fair value per share, Forfeited/canceled 106.55  
Weighted-average grant date fair value per share, Unvested restricted stock units/ awards outstanding, Ending balance 115.16 90.05
Weighted-average grant date fair value per share, Unvested and expected to vest restricted stock units/awards outstanding $ 115.98 $ 89.95
Time based restricted stock awards    
Class Of Stock [Line Items]    
Unvested restricted stock units/ awards outstanding, Beginning balance 20,789  
Granted 22,645 20,789
Vested (6,497)  
Unvested restricted stock units/ awards outstanding, Ending balance 36,937 20,789
Performance and time based restricted stock awards    
Class Of Stock [Line Items]    
Unvested restricted stock units/ awards outstanding, Beginning balance 20,785  
Granted 33,964 20,785
Vested (6,928)  
Unvested restricted stock units/ awards outstanding, Ending balance 47,821 20,785
Restricted stock awards    
Class Of Stock [Line Items]    
Unvested restricted stock units/ awards outstanding, Beginning balance 41,574  
Granted 56,609 41,574
Vested (13,425)  
Unvested restricted stock units/ awards outstanding, Ending balance 84,758 41,574
Unvested and expected to vest restricted stock units/awards outstanding 65,773 34,051
Weighted-average grant date fair value per share, Unvested restricted stock units/ awards outstanding, Beginning balance $ 91.52  
Weighted-average grant date fair value per share, Granted 130.89 $ 91.52
Weighted-average grant date fair value per share, Vested 91.52  
Weighted-average grant date fair value per share, Unvested restricted stock units/ awards outstanding, Ending balance 115.80 91.52
Weighted-average grant date fair value per share, Unvested and expected to vest restricted stock units/awards outstanding $ 115.85 $ 91.52