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)
3 Months Ended
Mar. 31, 2017
$ / shares
shares
Stock Options:  
Balance as of December 31, 2016 (shares) | shares 1,754,275
Granted (shares) | shares 180,765
Exercised (shares) | shares (29,412)
Forfeited (shares) | shares 0
Balance as of March 31, 2017 (shares) | shares 1,905,628
Weighted Average Exercise Price (in USD per share)  
Balance as of December 31, 2016 | $ / shares $ 42.12
Granted | $ / shares 100.81
Exercised | $ / shares 17.42
Forfeited | $ / shares 0.00
Balance as of March 31, 2017 | $ / shares $ 48.07
Restricted Stock [Member]  
Restricted Shares:  
Nonvested at December 31, 2015 (shares) | shares 308,700
Granted (shares) | shares 64,155
Exercised (shares) | shares (96,744)
Forfeited (shares) | shares (300)
Nonvested at June 30, 2016 (shares) | shares 275,811
Weighted- Average Grant Date Fair Value (in USD per share)  
Nonvested at December 31, 2015 | $ / shares $ 86.61
Granted | $ / shares 100.91
Exercised | $ / shares 79.68
Forfeited | $ / shares 97.92
Nonvested at March 31, 2016 | $ / shares $ 92.36