Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.1
Stockholders' Equity - Summary of Restricted Stock Activity (Details)
3 Months Ended
Mar. 31, 2019
$ / shares
shares
Time based restricted stock units  
Class Of Stock [Line Items]  
Unvested restricted stock units/ awards outstanding, Beginning balance 58,589
Granted 34,870
Vested (7,453)
Forfeited/canceled (54)
Unvested restricted stock units/ awards outstanding, Ending balance 85,952 [1]
Performance and time based restricted stock units  
Class Of Stock [Line Items]  
Unvested restricted stock units/ awards outstanding, Beginning balance 8,739
Vested (4,366)
Unvested restricted stock units/ awards outstanding, Ending balance 4,373 [1]
Restricted stock units  
Class Of Stock [Line Items]  
Unvested restricted stock units/ awards outstanding, Beginning balance 67,328
Granted 34,870
Vested (11,819)
Forfeited/canceled (54)
Unvested restricted stock units/ awards outstanding, Ending balance 90,325 [1]
Unvested and expected to vest restricted stock units/awards outstanding 85,159
Weighted-average grant date fair value per share, Unvested restricted stock units/ awards outstanding, Beginning balance | $ / shares $ 115.16
Weighted-average grant date fair value per share, Granted | $ / shares 106.97
Weighted-average grant date fair value per share, Vested | $ / shares 103.71
Weighted-average grant date fair value per share, Forfeited/canceled | $ / shares 91.52
Weighted-average grant date fair value per share, Unvested restricted stock units/ awards outstanding, Ending balance | $ / shares 113.51
Weighted-average grant date fair value per share, Unvested and expected to vest restricted stock units/awards outstanding | $ / shares $ 113.82
Time based restricted stock awards  
Class Of Stock [Line Items]  
Unvested restricted stock units/ awards outstanding, Beginning balance 36,937
Granted 26,778
Vested (6,319)
Forfeited/canceled (2,079)
Unvested restricted stock units/ awards outstanding, Ending balance 55,317 [1]
Performance and time based restricted stock awards  
Class Of Stock [Line Items]  
Unvested restricted stock units/ awards outstanding, Beginning balance 47,821
Granted 40,166
Vested (15,732)
Forfeited/canceled (3,839)
Unvested restricted stock units/ awards outstanding, Ending balance 68,416 [1]
Restricted stock awards  
Class Of Stock [Line Items]  
Unvested restricted stock units/ awards outstanding, Beginning balance 84,758
Granted 66,944
Vested (22,051)
Forfeited/canceled (5,918)
Unvested restricted stock units/ awards outstanding, Ending balance 123,733 [1]
Unvested and expected to vest restricted stock units/awards outstanding 92,218
Weighted-average grant date fair value per share, Unvested restricted stock units/ awards outstanding, Beginning balance | $ / shares $ 115.80
Weighted-average grant date fair value per share, Granted | $ / shares 106.97
Weighted-average grant date fair value per share, Vested | $ / shares 115.73
Weighted-average grant date fair value per share, Forfeited/canceled | $ / shares 100.62
Weighted-average grant date fair value per share, Unvested restricted stock units/ awards outstanding, Ending balance | $ / shares 112.15
Weighted-average grant date fair value per share, Unvested and expected to vest restricted stock units/awards outstanding | $ / shares $ 112.18
[1] Outstanding restricted stock units and restricted stock awards are based on the maximum payout of the targeted number of shares.