Share Repurchases (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Share Repurchases [Line Items]
Purchase of common stock		$ 0	$ 600,164
January 2015 Authorization [Member]
Share Repurchases [Line Items]
Number of shares authorized to be repurchased		15,000,000
Shares repurchased	1,510,124	0	8,228,542
Average price per share for repurchased shares (in dollars per share)	$ 66.24		$ 72.94
Remaining number of shares authorized to be repurchased		6,771,458
Purchase of common stock	$ 100,030		$ 600,164