Share-Based Compensation - Information pertaining to options oustanding - (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Share Based Compensation
Range of exercise prices, low end of range (in dollars per share)			$ 61.42	$ 61.42
Range of exercise prices, high end of range (in dollars per share)	$ 69.48	$ 66.32	$ 69.48	$ 66.32
Restricted Stock.
Vesting schedule of shares
Total	187,165		187,165		218,282