Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity (Stock Option Plan and Restricted Stock Activity) (Details)

v3.7.0.1
Stockholders' Equity (Stock Option Plan and Restricted Stock Activity) (Details)
6 Months Ended
Jun. 30, 2017
$ / shares
shares
Stock Options:  
Balance as of December 31, 2016 (shares) | shares 1,754,275
Granted (shares) | shares 198,101
Exercised (shares) | shares (80,872)
Forfeited (shares) | shares 0
Balance as of June 30, 2017 (shares) | shares 1,871,504
Weighted Average Exercise Price (in USD per share)  
Balance as of December 31, 2016 | $ / shares $ 42.12
Granted | $ / shares 101.93
Options exercised/RSUs vested | $ / shares 29.11
Forfeited | $ / shares 0.00
Balance as of June 30, 2017 | $ / shares $ 49.02
Restricted Stock [Member]  
Restricted Shares:  
Nonvested at December 31, 2016 (shares) | shares 308,700
Granted (shares) | shares 68,151
Exercised (shares) | shares (100,476)
Forfeited (shares) | shares (300)
Nonvested at June 30, 2017 (shares) | shares 276,075
Weighted- Average Grant Date Fair Value (in USD per share)  
Nonvested at December 31, 2016 | $ / shares $ 86.61
Granted | $ / shares 101.64
Options exercised/RSUs vested | $ / shares 81.15
Forfeited | $ / shares 97.92
Nonvested at June 30, 2017 | $ / shares $ 92.30