Share-Based Compensation - Information pertaining to options oustanding - (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 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	194,738		194,738		218,282