Stock Based Compensation - Options Rollforward (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning Balance | shares	99,671
Options Granted | shares	67,444
Ending Balance | shares	167,115
Options Expected to Vest | shares	103,040
Options Exerciseable | shares	64,075
Weighted Average Exercise Price [Abstract]
Outstanding at Beginning of Year | $ / shares	$ 71.73
Options Granted | $ / shares	72.12
Outstanding at End of Period | $ / shares	71.89
Options Expected to Vest | $ / shares	75.82
Options Exercisable | $ / shares	$ 65.57
Weighted Average Contractual Term [Abstract]
Weighted Average Remaining Contractual Term, Outstanding	5 years 8 months
Weighted Average Remaining Contractual Term, Expected to Vest	6 years 5 months
Weighted Average Remaining Contractual Term, Exercisable	4 years 5 months
Outstanding Options, Intrinsic Value | $	$ 2,317
Expected to Vest Options, Intrinsic Value | $	1,027
Exercisable Options, Intrinsic Value | $	$ 1,290