Repurchases of Common Stock (Narrative) (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Feb. 03, 2015
Class of Stock Disclosures [Abstract]
Additional board authorization			$ 250,000,000
Repurchased common shares (in shares)		1,840,318
Repurchased common shares (in usd per share)		$ 67.10
Repurchases of common stock	$ (60,758,000)	$ (123,489,000)