Stock Option Plans - Summary of Option Activity (Details)	9 Months Ended
	Sep. 30, 2016 USD ($) $ / shares shares
Number of Shares
Outstanding at beginning of period (in shares) | shares	860,274
Granted (in shares) | shares	226,500
Exercised (in shares) | shares	(219,956)
Expired/Forfeited (in shares) | shares	(2,500)
Outstanding at end of period (in shares) | shares	864,318
Exercisable at end of period (in shares) | shares	402,193
Weighted Average Exercise Price per share
Outstanding at beginning of period (in usd per share) | $ / shares	$ 46.58
Granted (in usd per share) | $ / shares	57.74
Exercised (in usd per share) | $ / shares	45.99
Expired/Forfeited (in usd per share) | $ / shares	40.35
Outstanding at end of period (in usd per share) | $ / shares	49.68
Exercisable at end of period (in usd per share) | $ / shares	$ 46.38
Aggregate Intrinsic Value
Outstanding at beginning of period | $	$ 4,237,456
Granted | $	2,006,790
Exercised | $	2,803,319
Expired/Forfeited | $
Outstanding at end of period | $	14,627,287
Exercisable at end of period | $	$ 8,130,910