Stock Repurchase (Schedule of Shares Repurchased) (Details) - $ / shares	1 Months Ended						6 Months Ended
	Jun. 30, 2015	May. 31, 2015	Apr. 30, 2015	Mar. 31, 2015	Feb. 28, 2015	Jan. 31, 2015	Jun. 30, 2015
Class of Stock Disclosures [Abstract]
Number of Shares Repurchased (in shares)	482,586	472,000	640,000	645,000	120,000	529,100	2,888,686
Average Price Paid Per Share (in dollars per share)	$ 67.19	$ 64.89	$ 61.20	$ 61.50	$ 61.07	$ 65.51	$ 63.66
Total Number of Shares Repurchased as Part of Publicly Announced Programs (in shares)	482,586	472,000	640,000	645,000	120,000	529,100	2,888,686