Stock Based Compensation Plans (Employee Stock Purchase Plan - Summary) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Employee Stock Purchase Plan - Shares Issued	168,962	157,856	167,260
Minimum [Member]
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Employee Stock Purchase Plan - Purchase Price Per Share	$ 90.87	$ 84.6	$ 69.27
Maximum [Member]
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Employee Stock Purchase Plan - Purchase Price Per Share	$ 90.55	$ 86.67	$ 73.7